Method for signaling output layer set with sub picture

ABSTRACT

There is included a method and apparatus comprising computer code configured to cause a processor or processors to perform obtaining video data, parsing a video parameter set (VPS) syntax of the video data, determining whether a value of a syntax element of the VPS syntax indicates a picture order count (POC) value of an access unit (AU) of the video data, and setting at least one of a plurality of pictures, slices, and tiles of the video data to the AU based on the value of the syntax element.

CROSS REFERENCE TO RELATED APPLICATION

The present application claims priority to provisional application U.S.62/904,338 filed on Sep. 23, 2019 which is hereby expressly incorporatedby reference, in its entirety, into the present application.

BACKGROUND 1. Field

The disclosed subject matter relates to video coding and decoding, andmore specifically, to the signaling of profile/tier/level informationfor support of temporal/spatial scalability with subpicturepartitioning.

2. Description of Related Art

Video coding and decoding using inter-picture prediction with motioncompensation has been known for decades. Uncompressed digital video canconsist of a series of pictures, each picture having a spatial dimensionof, for example, 1920×1080 luminance samples and associated chrominancesamples. The series of pictures can have a fixed or variable picturerate (informally also known as frame rate), of, for example 60 picturesper second or 60 Hz. Uncompressed video has significant bitraterequirements. For example, 1080p60 4:2:0 video at 8 bit per sample(1920×1080 luminance sample resolution at 60 Hz frame rate) requiresclose to 1.5 Gbit/s bandwidth. An hour of such video requires more than600 GByte of storage space.

One purpose of video coding and decoding can be the reduction ofredundancy in the input video signal, through compression. Compressioncan help reducing aforementioned bandwidth or storage spacerequirements, in some cases by two orders of magnitude or more. Bothlossless and lossy compression, as well as a combination thereof can beemployed. Lossless compression refers to techniques where an exact copyof the original signal can be reconstructed from the compressed originalsignal. When using lossy compression, the reconstructed signal may notbe identical to the original signal, but the distortion between originaland reconstructed signal is small enough to make the reconstructedsignal useful for the intended application. In the case of video, lossycompression is widely employed. The amount of distortion tolerateddepends on the application; for example, users of certain consumerstreaming applications may tolerate higher distortion than users oftelevision contribution applications. The compression ratio achievablecan reflect that: higher allowable/tolerable distortion can yield highercompression ratios.

A video encoder and decoder can utilize techniques from several broadcategories, including, for example, motion compensation, transform,quantization, and entropy coding, some of which will be introducedbelow.

Historically, video encoders and decoders tended to operate on a givenpicture size that was, in most cases, defined and stayed constant for acoded video sequence (CVS), Group of Pictures (GOP), or a similarmulti-picture timeframe. For example, in MPEG-2, system designs areknown to change the horizontal resolution (and, thereby, the picturesize) dependent on factors such as activity of the scene, but only at Ipictures, hence typically for a GOP. The resampling of referencepictures for use of different resolutions within a CVS is known, forexample, from ITU-T Rec. H.263 Annex P. However, here the picture sizedoes not change, only the reference pictures are being resampled,resulting potentially in only parts of the picture canvas being used (incase of downsampling), or only parts of the scene being captured (incase of upsampling). Further, H.263 Annex Q allows the resampling of anindividual macroblock by a factor of two (in each dimension), upward ordownward. Again, the picture size remains the same. The size of amacroblock is fixed in H.263, and therefore does not need to besignaled.

Changes of picture size in predicted pictures became more mainstream inmodern video coding. For example, VP9 allows reference pictureresampling and change of resolution for a whole picture. Similarly,certain proposals made towards VVC (including, for example, Hendry, et.al, “On adaptive resolution change (ARC) for VVC”, Joint Video Teamdocument WET-M0135-v1, Jan. 9-19, 2019, incorporated herein in itsentirety) allow for resampling of whole reference pictures todifferent—higher or lower—resolutions. In that document, differentcandidate resolutions are suggested to be coded in the sequenceparameter set and referred to by per-picture syntax elements in thepicture parameter set.

SUMMARY

There is included a method and apparatus comprising memory configured tostore computer program code and a processor or processors configured toaccess the computer program code and operate as instructed by thecomputer program code. The computer program code includes obtaining codeconfigured to cause the at least one processor to obtain video data,parsing code configured to cause the at least one processor to parse avideo parameter set (VPS) syntax of the video data, determining codeconfigured to cause the at least one processor to determine whether avalue of a syntax element of the VPS syntax indicates a picture ordercount (POC) value of an access unit (AU) of the video data, and settingcode configured to cause the at least one processor to set at least oneof a plurality of pictures, slices, and tiles of the video data to theAU based on the value of the syntax element.

According to exemplary embodiments, the value of the syntax elementindicates a number consecutive ones of the plurality of pictures,slices, and tiles of the video data to be set to the AU.

According to exemplary embodiments, the VPS syntax is contained in a VPSof the video data and identifying a number of at least one type ofenhancement layers of the video data.

According to exemplary embodiments, the determining code is furtherconfigured to cause the at least one processor to determine whether theVPS syntax comprises a flag indicating whether the POC value increasesuniformly per AU.

According to exemplary embodiments, there is further calculating codeconfigured to cause the at least one processor to calculate, in responseto determining that the VPS comprises the flag and that the flagindicates that the POC value does not increase uniformly per AU, anaccess unit count (AUC) from the POC value and a picture level value ofthe video data.

According to exemplary embodiments, there is further calculating codeconfigured to cause the at least one processor to calculate, in responseto determining that the VPS comprises the flag and that the flagindicates that the POC value does increase uniformly per AU, an accessunit count (AUC) from the POC value and a sequence level value of thevideo data.

According to exemplary embodiments, the determining code is furtherconfigured to cause the at least one processor to determine whether theVPS syntax comprises a flag indicating whether at least one of thepictures is divided into a plurality of sub-regions.

According to exemplary embodiments, the setting code is furtherconfigured to cause the at least one processor to set, in response todetermining that the VPS syntax comprises the flag and that the flagindicates that the at least one of the pictures is not divided into theplurality of sub-regions, an input picture size of the at least one ofthe pictures to a coded picture size signaled in a sequence parameterset (SPS) of the video data.

According to exemplary embodiments, the determining code is furtherconfigured to cause the at least one processor to determine, in responseto determining that the VPS syntax comprises the flag and that the flagindicates that the at least one of the pictures is divided into theplurality of sub-regions, whether the SPS comprises syntax elementssignaling offsets corresponding to a layer of the video data.

According to exemplary embodiments, the offsets comprise an offset in anwidth direction and an offset in a height direction.

BRIEF DESCRIPTION OF THE DRAWINGS

Further features, the nature, and various advantages of the disclosedsubject matter will be more apparent from the following detaileddescription and the accompanying drawings in which:

FIG. 1 is a schematic illustration of a simplified block diagram of acommunication system in accordance with embodiments.

FIG. 2 is a schematic illustration of a simplified block diagram of acommunication system in accordance with embodiments.

FIG. 3 is a schematic illustration of a simplified block diagram of adecoder in accordance with embodiments.

FIG. 4 is a schematic illustration of a simplified block diagram of anencoder in accordance with embodiments.

FIG. 5A is a schematic illustration of options for signaling ARCparameters in accordance with related art.

FIG. 5B is a schematic illustration of options for signaling ARCparameters in accordance with related art.

FIG. 5C is a schematic illustration of options for signaling ARCparameters in accordance with embodiments.

FIG. 5D is a schematic illustration of options for signaling ARCparameters in accordance with embodiments.

FIG. 5E is a schematic illustration of options for signaling ARCparameters in accordance with embodiments.

FIG. 6 is an example of a syntax table in accordance with embodiments.

FIG. 7 is a schematic illustration of a computer system in accordancewith embodiments.

FIG. 8 is an example of prediction structure for scalability withadaptive resolution change.

FIG. 9 is an example of a syntax table in accordance with embodiments.

FIG. 10 is a schematic illustration of a simplified block diagram ofparsing and decoding poc cycle per access unit and access unit countvalue in accordance with embodiments.

FIG. 11 is a schematic illustration of a video bitstream structurecomprising multi-layered sub-pictures in accordance with embodiments.

FIG. 12 is a schematic illustration of a display of the selectedsub-picture with an enhanced resolution in accordance with embodiments.

FIG. 13 is a block diagram of the decoding and display process for avideo bitstream comprising multi-layered sub-pictures in accordance withembodiments.

FIG. 14 is a schematic illustration of 360 video display with anenhancement layer of a sub-picture in accordance with embodiments.

FIG. 15 is an example of a layout information of sub-pictures and itscorresponding layer and picture prediction structure in accordance withembodiments.

FIG. 16 is an example of a layout information of sub-pictures and itscorresponding layer and picture prediction structure, with spatialscalability modality of local region in accordance with embodiments.

FIG. 17 is an example of a syntax table for sub-picture layoutinformation in accordance with embodiments.

FIG. 18 is an example of a syntax table of SEI message for sub-picturelayout information in accordance with embodiments.

FIG. 19 is an example of a syntax table to indicate output layers andprofile/tier/level information for each output layer set in accordancewith embodiments.

FIG. 20 is an example of a syntax table to indicate output layer mode onfor each output layer set in accordance with embodiments.

FIG. 21 is an example of a syntax table to indicate the presentsubpicture of each layer for each output layer set in accordance withembodiments.

DETAILED DESCRIPTION

The proposed features discussed below may be used separately or combinedin any order. Further, the embodiments may be implemented by processingcircuitry (e.g., one or more processors or one or more integratedcircuits). In one example, the one or more processors execute a programthat is stored in a non-transitory computer-readable medium.

Recently, compressed domain aggregation or extraction of multiplesemantically independent picture parts into a single video picture hasgained some attention. In particular, in the context of, for example,360 coding or certain surveillance applications, multiple semanticallyindependent source pictures (for examples the six cube surface of acube-projected 360 scene, or individual camera inputs in case of amulti-camera surveillance setup) may require separate adaptiveresolution settings to cope with different per-scene activity at a givenpoint in time. In other words, encoders, at a given point in time, maychoose to use different resampling factors for different semanticallyindependent pictures that make up the whole 360 or surveillance scene.When combined into a single picture, that, in turn, requires thatreference picture resampling is performed, and adaptive resolutioncoding signaling is available, for parts of a coded picture.

FIG. 1 illustrates a simplified block diagram of a communication system(100) according to an embodiment of the present disclosure. The system(100) may include at least two terminals (110, 120) interconnected via anetwork (150). For unidirectional transmission of data, a first terminal(110) may code video data at a local location for transmission to theother terminal (120) via the network (150). The second terminal (120)may receive the coded video data of the other terminal from the network(150), decode the coded data and display the recovered video data.Unidirectional data transmission may be common in media servingapplications and the like.

FIG. 1 illustrates a second pair of terminals (130, 140) provided tosupport bidirectional transmission of coded video that may occur, forexample, during videoconferencing. For bidirectional transmission ofdata, each terminal (130, 140) may code video data captured at a locallocation for transmission to the other terminal via the network (150).Each terminal (130, 140) also may receive the coded video datatransmitted by the other terminal, may decode the coded data and maydisplay the recovered video data at a local display device.

In FIG. 1, the terminals (110, 120, 130, 140) may be illustrated asservers, personal computers and smart phones but the principles of thepresent disclosure may be not so limited. Embodiments of the presentdisclosure find application with laptop computers, tablet computers,media players and/or dedicated video conferencing equipment. The network(150) represents any number of networks that convey coded video dataamong the terminals (110, 120, 130, 140), including for example wirelineand/or wireless communication networks. The communication network (150)may exchange data in circuit-switched and/or packet-switched channels.Representative networks include telecommunications networks, local areanetworks, wide area networks and/or the Internet. For the purposes ofthe present discussion, the architecture and topology of the network(150) may be immaterial to the operation of the present disclosureunless explained herein below.

FIG. 2 illustrates, as an example for an application for the disclosedsubject matter, the placement of a video encoder and decoder in astreaming environment. The disclosed subject matter can be equallyapplicable to other video enabled applications, including, for example,video conferencing, digital TV, storing of compressed video on digitalmedia including CD, DVD, memory stick and the like, and so on.

A streaming system may include a capture subsystem (213), that caninclude a video source (201), for example a digital camera, creating afor example uncompressed video sample stream (202). That sample stream(202), depicted as a bold line to emphasize a high data volume whencompared to encoded video bitstreams, can be processed by an encoder(203) coupled to the camera (201). The encoder (203) can includehardware, software, or a combination thereof to enable or implementaspects of the disclosed subject matter as described in more detailbelow. The encoded video bitstream (204), depicted as a thin line toemphasize the lower data volume when compared to the sample stream, canbe stored on a streaming server (205) for future use. One or morestreaming clients (206, 208) can access the streaming server (205) toretrieve copies (207, 209) of the encoded video bitstream (204). Aclient (206) can include a video decoder (210) which decodes theincoming copy of the encoded video bitstream (207) and creates anoutgoing video sample stream (211) that can be rendered on a display(212) or other rendering device (not depicted). In some streamingsystems, the video bitstreams (204, 207, 209) can be encoded accordingto certain video coding/compression standards. Examples of thosestandards include ITU-T Recommendation H.265. Under development is avideo coding standard informally known as Versatile Video Coding or VVC.The disclosed subject matter may be used in the context of VVC.

FIG. 3 may be a functional block diagram of a video decoder (210)according to an embodiment of the present disclosure.

A receiver (310) may receive one or more codec video sequences to bedecoded by the decoder (210); in the same or another embodiment, onecoded video sequence at a time, where the decoding of each coded videosequence is independent from other coded video sequences. The codedvideo sequence may be received from a channel (312), which may be ahardware/software link to a storage device which stores the encodedvideo data. The receiver (310) may receive the encoded video data withother data, for example, coded audio data and/or ancillary data streams,that may be forwarded to their respective using entities (not depicted).The receiver (310) may separate the coded video sequence from the otherdata. To combat network jitter, a buffer memory (315) may be coupled inbetween receiver (310) and entropy decoder/parser (320) (“parser”henceforth). When receiver (310) is receiving data from a store/forwarddevice of sufficient bandwidth and controllability, or from anisosychronous network, the buffer (315) may not be needed, or can besmall. For use on best effort packet networks such as the Internet, thebuffer (315) may be required, can be comparatively large and canadvantageously of adaptive size.

The video decoder (210) may include an parser (320) to reconstructsymbols (321) from the entropy coded video sequence. Categories of thosesymbols include information used to manage operation of the decoder(210), and potentially information to control a rendering device such asa display (212) that is not an integral part of the decoder but can becoupled to it, as was shown in FIG. 2. The control information for therendering device(s) may be in the form of Supplementary EnhancementInformation (SEI messages) or Video Usability Information (VUI)parameter set fragments (not depicted). The parser (320) mayparse/entropy-decode the coded video sequence received. The coding ofthe coded video sequence can be in accordance with a video codingtechnology or standard, and can follow principles well known to a personskilled in the art, including variable length coding, Huffman coding,arithmetic coding with or without context sensitivity, and so forth. Theparser (320) may extract from the coded video sequence, a set ofsubgroup parameters for at least one of the subgroups of pixels in thevideo decoder, based upon at least one parameters corresponding to thegroup. Subgroups can include Groups of Pictures (GOPs), pictures, tiles,slices, macroblocks, Coding Units (CUs), blocks, Transform Units (TUs),Prediction Units (PUs) and so forth. The entropy decoder/parser may alsoextract from the coded video sequence information such as transformcoefficients, quantizer parameter values, motion vectors, and so forth.

The parser (320) may perform entropy decoding/parsing operation on thevideo sequence received from the buffer (315), so to create symbols(321).

Reconstruction of the symbols (321) can involve multiple different unitsdepending on the type of the coded video picture or parts thereof (suchas: inter and intra picture, inter and intra block), and other factors.Which units are involved, and how, can be controlled by the subgroupcontrol information that was parsed from the coded video sequence by theparser (320). The flow of such subgroup control information between theparser (320) and the multiple units below is not depicted for clarity.

Beyond the functional blocks already mentioned, decoder 210 can beconceptually subdivided into a number of functional units as describedbelow. In a practical implementation operating under commercialconstraints, many of these units interact closely with each other andcan, at least partly, be integrated into each other. However, for thepurpose of describing the disclosed subject matter, the conceptualsubdivision into the functional units below is appropriate.

A first unit is the scaler/inverse transform unit (351). Thescaler/inverse transform unit (351) receives quantized transformcoefficient as well as control information, including which transform touse, block size, quantization factor, quantization scaling matrices,etc. as symbol(s) (321) from the parser (320). It can output blockscomprising sample values, that can be input into aggregator (355).

In some cases, the output samples of the scaler/inverse transform (351)can pertain to an intra coded block; that is: a block that is not usingpredictive information from previously reconstructed pictures, but canuse predictive information from previously reconstructed parts of thecurrent picture. Such predictive information can be provided by an intrapicture prediction unit (352). In some cases, the intra pictureprediction unit (352) generates a block of the same size and shape ofthe block under reconstruction, using surrounding already reconstructedinformation fetched from the current (partly reconstructed) picture(356). The aggregator (355), in some cases, adds, on a per sample basis,the prediction information the intra prediction unit (352) has generatedto the output sample information as provided by the scaler/inversetransform unit (351).

In other cases, the output samples of the scaler/inverse transform unit(351) can pertain to an inter coded, and potentially motion compensatedblock. In such a case, a Motion Compensation Prediction unit (353) canaccess reference picture memory (357) to fetch samples used forprediction. After motion compensating the fetched samples in accordancewith the symbols (321) pertaining to the block, these samples can beadded by the aggregator (355) to the output of the scaler/inversetransform unit (in this case called the residual samples or residualsignal) so to generate output sample information. The addresses withinthe reference picture memory form where the motion compensation unitfetches prediction samples can be controlled by motion vectors,available to the motion compensation unit in the form of symbols (321)that can have, for example X, Y, and reference picture components.Motion compensation also can include interpolation of sample values asfetched from the reference picture memory when sub-sample exact motionvectors are in use, motion vector prediction mechanisms, and so forth.

The output samples of the aggregator (355) can be subject to variousloop filtering techniques in the loop filter unit (356). Videocompression technologies can include in-loop filter technologies thatare controlled by parameters included in the coded video bitstream andmade available to the loop filter unit (356) as symbols (321) from theparser (320), but can also be responsive to meta-information obtainedduring the decoding of previous (in decoding order) parts of the codedpicture or coded video sequence, as well as responsive to previouslyreconstructed and loop-filtered sample values.

The output of the loop filter unit (356) can be a sample stream that canbe output to the render device (212) as well as stored in the referencepicture memory (356) for use in future inter-picture prediction.

Certain coded pictures, once fully reconstructed, can be used asreference pictures for future prediction. Once a coded picture is fullyreconstructed and the coded picture has been identified as a referencepicture (by, for example, parser (320)), the current reference picture(356) can become part of the reference picture buffer (357), and a freshcurrent picture memory can be reallocated before commencing thereconstruction of the following coded picture.

The video decoder 320 may perform decoding operations according to apredetermined video compression technology that may be documented in astandard, such as ITU-T Rec. H.265. The coded video sequence may conformto a syntax specified by the video compression technology or standardbeing used, in the sense that it adheres to the syntax of the videocompression technology or standard, as specified in the videocompression technology document or standard and specifically in theprofiles document therein. Also necessary for compliance can be that thecomplexity of the coded video sequence is within bounds as defined bythe level of the video compression technology or standard. In somecases, levels restrict the maximum picture size, maximum frame rate,maximum reconstruction sample rate (measured in, for example megasamplesper second), maximum reference picture size, and so on. Limits set bylevels can, in some cases, be further restricted through HypotheticalReference Decoder (HRD) specifications and metadata for HRD buffermanagement signaled in the coded video sequence.

In an embodiment, the receiver (310) may receive additional (redundant)data with the encoded video. The additional data may be included as partof the coded video sequence(s). The additional data may be used by thevideo decoder (320) to properly decode the data and/or to moreaccurately reconstruct the original video data. Additional data can bein the form of, for example, temporal, spatial, or SNR (signal tonoise/quality scalability) enhancement layers, redundant slices,redundant pictures, forward error correction codes, and so on.

FIG. 4 may be a functional block diagram of a video encoder (203)according to an embodiment of the present disclosure.

The encoder (203) may receive video samples from a video source (201)(that is not part of the encoder) that may capture video image(s) to becoded by the encoder (203).

The video source (201) may provide the source video sequence to be codedby the encoder (203) in the form of a digital video sample stream thatcan be of any suitable bit depth (for example: 8 bit, 10 bit, 12 bit, .. . ), any colorspace (for example, BT.601 Y CrCB, RGB, . . . ) and anysuitable sampling structure (for example Y CrCb 4:2:0, Y CrCb 4:4:4). Ina media serving system, the video source (201) may be a storage devicestoring previously prepared video. In a videoconferencing system, thevideo source (203) may be a camera that captures local image informationas a video sequence. Video data may be provided as a plurality ofindividual pictures that impart motion when viewed in sequence. Thepictures themselves may be organized as a spatial array of pixels,wherein each pixel can comprise one or more sample depending on thesampling structure, color space, etc. in use. A person skilled in theart can readily understand the relationship between pixels and samples.The description below focusses on samples.

According to an embodiment, the encoder (203) may code and compress thepictures of the source video sequence into a coded video sequence (443)in real time or under any other time constraints as required by theapplication. Enforcing appropriate coding speed is one function ofController (450). Controller controls other functional units asdescribed below and is functionally coupled to these units. The couplingis not depicted for clarity. Parameters set by controller can includerate control related parameters (picture skip, quantizer, lambda valueof rate-distortion optimization techniques, . . . ), picture size, groupof pictures (GOP) layout, maximum motion vector search range, and soforth. A person skilled in the art can readily identify other functionsof controller (450) as they may pertain to video encoder (203) optimizedfor a certain system design.

Some video encoders operate in what a person skilled in the are readilyrecognizes as a “coding loop”. As an oversimplified description, acoding loop can consist of the encoding part of an encoder (430)(“source coder” henceforth) (responsible for creating symbols based onan input picture to be coded, and a reference picture(s)), and a (local)decoder (433) embedded in the encoder (203) that reconstructs thesymbols to create the sample data a (remote) decoder also would create(as any compression between symbols and coded video bitstream islossless in the video compression technologies considered in thedisclosed subject matter). That reconstructed sample stream is input tothe reference picture memory (434). As the decoding of a symbol streamleads to bit-exact results independent of decoder location (local orremote), the reference picture buffer content is also bit exact betweenlocal encoder and remote encoder. In other words, the prediction part ofan encoder “sees” as reference picture samples exactly the same samplevalues as a decoder would “see” when using prediction during decoding.This fundamental principle of reference picture synchronicity (andresulting drift, if synchronicity cannot be maintained, for examplebecause of channel errors) is well known to a person skilled in the art.

The operation of the “local” decoder (433) can be the same as of a“remote” decoder (210), which has already been described in detail abovein conjunction with FIG. 3. Briefly referring also to FIG. 3, however,as symbols are available and en/decoding of symbols to a coded videosequence by entropy coder (445) and parser (320) can be lossless, theentropy decoding parts of decoder (210), including channel (312),receiver (310), buffer (315), and parser (320) may not be fullyimplemented in local decoder (433).

An observation that can be made at this point is that any decodertechnology except the parsing/entropy decoding that is present in adecoder also necessarily needs to be present, in substantially identicalfunctional form, in a corresponding encoder. For this reason, thedisclosed subject matter focusses on decoder operation. The descriptionof encoder technologies can be abbreviated as they are the inverse ofthe comprehensively described decoder technologies. Only in certainareas a more detail description is required and provided below.

As part of its operation, the source coder (430) may perform motioncompensated predictive coding, which codes an input frame predictivelywith reference to one or more previously-coded frames from the videosequence that were designated as “reference frames.” In this manner, thecoding engine (432) codes differences between pixel blocks of an inputframe and pixel blocks of reference frame(s) that may be selected asprediction reference(s) to the input frame.

The local video decoder (433) may decode coded video data of frames thatmay be designated as reference frames, based on symbols created by thesource coder (430). Operations of the coding engine (432) mayadvantageously be lossy processes. When the coded video data may bedecoded at a video decoder (not shown in FIG. 4), the reconstructedvideo sequence typically may be a replica of the source video sequencewith some errors. The local video decoder (433) replicates decodingprocesses that may be performed by the video decoder on reference framesand may cause reconstructed reference frames to be stored in thereference picture cache (434). In this manner, the encoder (203) maystore copies of reconstructed reference frames locally that have commoncontent as the reconstructed reference frames that will be obtained by afar-end video decoder (absent transmission errors).

The predictor (435) may perform prediction searches for the codingengine (432). That is, for a new frame to be coded, the predictor (435)may search the reference picture memory (434) for sample data (ascandidate reference pixel blocks) or certain metadata such as referencepicture motion vectors, block shapes, and so on, that may serve as anappropriate prediction reference for the new pictures. The predictor(435) may operate on a sample block-by-pixel block basis to findappropriate prediction references. In some cases, as determined bysearch results obtained by the predictor (435), an input picture mayhave prediction references drawn from multiple reference pictures storedin the reference picture memory (434).

The controller (450) may manage coding operations of the video coder(430), including, for example, setting of parameters and subgroupparameters used for encoding the video data.

Output of all aforementioned functional units may be subjected toentropy coding in the entropy coder (445). The entropy coder translatesthe symbols as generated by the various functional units into a codedvideo sequence, by loss-less compressing the symbols according totechnologies known to a person skilled in the art as, for exampleHuffman coding, variable length coding, arithmetic coding, and so forth.

The transmitter (440) may buffer the coded video sequence(s) as createdby the entropy coder (445) to prepare it for transmission via acommunication channel (460), which may be a hardware/software link to astorage device which would store the encoded video data. The transmitter(440) may merge coded video data from the video coder (430) with otherdata to be transmitted, for example, coded audio data and/or ancillarydata streams (sources not shown).

The controller (450) may manage operation of the encoder (203). Duringcoding, the controller (450) may assign to each coded picture a certaincoded picture type, which may affect the coding techniques that may beapplied to the respective picture. For example, pictures often may beassigned as one of the following frame types:

An Intra Picture (I picture) may be one that may be coded and decodedwithout using any other frame in the sequence as a source of prediction.Some video codecs allow for different types of Intra pictures,including, for example Independent Decoder Refresh Pictures. A personskilled in the art is aware of those variants of I pictures and theirrespective applications and features.

A Predictive picture (P picture) may be one that may be coded anddecoded using intra prediction or inter prediction using at most onemotion vector and reference index to predict the sample values of eachblock.

A Bi-directionally Predictive Picture (B Picture) may be one that may becoded and decoded using intra prediction or inter prediction using atmost two motion vectors and reference indices to predict the samplevalues of each block. Similarly, multiple-predictive pictures can usemore than two reference pictures and associated metadata for thereconstruction of a single block.

Source pictures commonly may be subdivided spatially into a plurality ofsample blocks (for example, blocks of 4×4, 8×8, 4×8, or 16×16 sampleseach) and coded on a block-by-block basis. Blocks may be codedpredictively with reference to other (already coded) blocks asdetermined by the coding assignment applied to the blocks' respectivepictures. For example, blocks of I pictures may be codednon-predictively or they may be coded predictively with reference toalready coded blocks of the same picture (spatial prediction or intraprediction). Pixel blocks of P pictures may be coded non-predictively,via spatial prediction or via temporal prediction with reference to onepreviously coded reference pictures. Blocks of B pictures may be codednon-predictively, via spatial prediction or via temporal prediction withreference to one or two previously coded reference pictures.

The video coder (203) may perform coding operations according to apredetermined video coding technology or standard, such as ITU-T Rec.H.265. In its operation, the video coder (203) may perform variouscompression operations, including predictive coding operations thatexploit temporal and spatial redundancies in the input video sequence.The coded video data, therefore, may conform to a syntax specified bythe video coding technology or standard being used.

In an embodiment, the transmitter (440) may transmit additional datawith the encoded video. The video coder (430) may include such data aspart of the coded video sequence. Additional data may comprisetemporal/spatial/SNR enhancement layers, other forms of redundant datasuch as redundant pictures and slices, Supplementary EnhancementInformation (SEI) messages, Visual Usability Information (VUI) parameterset fragments, and so on.

Before describing certain aspects of the disclosed subject matter inmore detail, a few terms need to be introduced that will be referred toin the remainder of this description.

Sub-Picture henceforth refers to an, in some cases, rectangulararrangement of samples, blocks, macroblocks, coding units, or similarentities that are semantically grouped, and that may be independentlycoded in changed resolution. One or more sub-pictures may for a picture.One or more coded sub-pictures may form a coded picture. One or moresub-pictures may be assembled into a picture, and one or more subpictures may be extracted from a picture. In certain environments, oneor more coded sub-pictures may be assembled in the compressed domainwithout transcoding to the sample level into a coded picture, and in thesame or certain other cases, one or more coded sub-pictures may beextracted from a coded picture in the compressed domain.

Adaptive Resolution Change (ARC) henceforth refers to mechanisms thatallow the change of resolution of a picture or sub-picture within acoded video sequence, by the means of, for example, reference pictureresampling. ARC parameters henceforth refer to the control informationrequired to perform adaptive resolution change, that may include, forexample, filter parameters, scaling factors, resolutions of outputand/or reference pictures, various control flags, and so forth.

Above description is focused on coding and decoding a single,semantically independent coded video picture. Before describing theimplication of coding/decoding of multiple sub pictures with independentARC parameters and its implied additional complexity, options forsignaling ARC parameters shall be described.

Referring to FIG. 5A-E, shown are several novel options for signalingARC parameters. As noted with each of the options, they have certainadvantages and certain disadvantages from a coding efficiency,complexity, and architecture viewpoint. A video coding standard ortechnology may choose one or more of these options, or options knownfrom previous art, for signaling ARC parameters. The options may not bemutually exclusive, and conceivably may be interchanged based onapplication needs, standards technology involved, or encoder's choice.

Classes of ARC parameters may include:

-   -   up/downsample factors, separate or combined in X and Y        dimension,    -   up/downsample factors, with an addition of a temporal dimension,        indicating constant speed zoom in/out for a given number of        pictures,    -   any of the above two may involve the coding of one or more        presumably short syntax elements that may point into a table        containing the factor(s),    -   resolution, in X or Y dimension, in units of samples, blocks,        macroblocks, CUs, or any other suitable granularity, of the        input picture, output picture, reference picture, coded picture,        combined or separately (If there are more than one resolution        (such as, for example, one for input picture, one for reference        picture) then, in certain cases, one set of values may be        inferred to from another set of values. Such could be gated, for        example, by the use of flags. For a more detailed example, see        below),    -   “warping” coordinates akin those used in H.263 Annex P, again in        a suitable granularity as described above (H.263 Annex P defines        one efficient way to code such warping coordinates, but other,        potentially more efficient ways are conceivably also be devised.        For example, according to embodiments the variable length        reversible, “Huffman”-style coding of warping coordinates of        Annex P is replaced by a suitable length binary coding, where        the length of the binary code word could, for example, be        derived from a maximum picture size, possibly multiplied by a        certain factor and offset by a certain value, so to allow for        “warping” outside of the maximum picture size's boundaries),        and/or    -   up or downsample filter parameters. In the easiest case, there        may be only a single filter for up and/or downsampling. However,        in certain cases, it can be advantageous to allow more        flexibility in filter design, and that may require to signaling        of filter parameters. Such parameters may be selected through an        index in a list of possible filter designs, the filter may be        fully specified (for example through a list of filter        coefficients, using suitable entropy coding techniques), the        filter may be implicitly selected through up/downsample ratios        according which in turn are signaled according to any of the        mechanisms mentioned above, and so forth.

Henceforth, the description assumes the coding of a finite set ofup/downsample factors (the same factor to be used in both X and Ydimension), indicated through a codeword. That codeword canadvantageously be variable length coded, for example using theExt-Golomb code common for certain syntax elements in video codingspecifications such as H.264 and H.265. One suitable mapping of valuesto up/downsample factors can, for example, be according to the followingtable

TABLE 1 Codeword Ext-Golomb Code Original/Target resolution 0 1 1/1 1010 1/1.5 (upscale by 50%) 2 011 1.5/1 (downscale by 50%) 3 00100 1/2(upscale by 100%) 4 00101 2/1 (downscale by 100%)

Many similar mappings could be devised according to the needs of anapplication and the capabilities of the up and downscale mechanismsavailable in a video compression technology or standard. The table couldbe extended to more values. Values may also be represented by entropycoding mechanisms other than Ext-Golomb codes, for example using binarycoding. That may have certain advantages when the resampling factorswere of interest outside the video processing engines (encoder anddecoder foremost) themselves, for example by MANEs. It should be notedthat, for the (presumably) most common case where no resolution changeis required, an Ext-Golomb code can be chosen that is short; in thetable above, only a single bit. That can have a coding efficiencyadvantage over using binary codes for the most common case.

The number of entries in the table, as well as their semantics may befully or partially configurable. For example, the basic outline of thetable may be conveyed in a “high” parameter set such as a sequence ordecoder parameter set. Alternatively or in addition, one or more suchtables may be defined in a video coding technology or standard, and maybe selected through for example a decoder or sequence parameter set.

Henceforth, we describe how an upsample/downsample factor (ARCinformation), coded as described above, may be included in a videocoding technology or standard syntax. Similar considerations may applyto one, or a few, codewords controlling up/downsample filters. See belowfor a discussion when comparatively large amounts of data are requiredfor a filter or other data structures.

As shown in the example of FIG. 5A, the illustration (500A) shows thatH.263 Annex P includes the ARC information 502 in the form of fourwarping coordinates into the picture header 501, specifically in theH.263 PLUSPTYPE (503) header extension. This can be a sensible designchoice when a) there is a picture header available, and b) frequentchanges of the ARC information are expected. However, the overhead whenusing H.263-style signaling can be quite high, and scaling factors maynot pertain among picture boundaries as picture header can be oftransient nature. Further, as shown in the example of FIG. 5B, theillustration (500B) shows that JVET-M0135 includes PPS information(504), ARC ref information (505), SPS information (507), and Target ResTable information (506).

According to exemplary embodiments, FIG. 5C illustrates example (500C)in which there is shown tile group header information (508) and ARCinformation (509); FIG. 5D illustrates example (500D) in which there isshown a tile group header information (514), an ARC ref information(513), SPS information (516) and ARC information (515), and FIG. 5Eillustrates example (500E) in which there is shown adaptation parameterset(s) (APS) information (511) and ARC information (512).

JVCET-M135-v1 includes the ARC reference information (505) (an index)located in a picture parameter set (504), indexing a table (506)including target resolutions that in turn is located inside a sequenceparameter set (507). The placement of the possible resolution in a table(506) in the sequence parameter set (507) can, according to verbalstatements made by the authors, be justified by using the SPS as aninteroperability negotiation point during capability exchange.Resolution can change, within the limits set by the values in the table(506) from picture to picture by referencing the appropriate pictureparameter set (504).

Still referring to FIG. 5, the following additional options may exist toconvey ARC information in a video bitstream. Each of those options hascertain advantages over existing art as described above. The options maybe simultaneously present in the same video coding technology orstandard.

In an embodiment, ARC information (509) such as a resampling (zoom)factor may be present in a slice header, GOB header, tile header, ortile group header (tile group header henceforth) (508). This can beadequate of the ARC information is small, such as a single variablelength ue(v) or fixed length codeword of a few bits, for example asshown above. Having the ARC information in a tile group header directlyhas the additional advantage of the ARC information may be applicable toa sub picture represented by, for example, that tile group, rather thanthe whole picture. See also below. In addition, even if the videocompression technology or standard envisions only whole picture adaptiveresolution changes (in contrast to, for example, tile group basedadaptive resolution changes), putting the ARC information into the tilegroup header vis a vis putting it into an H.263-style picture header hascertain advantages from an error resilience viewpoint.

In the same or another embodiment, the ARC information (512) itself maybe present in an appropriate parameter set (511) such as, for example, apicture parameter set, header parameter set, tile parameter set,adapation parameter set, and so forth (Adapation parameter setdepicted). The scope of that parameter set can advantageously be nolarger than a picture, for example a tile group. The use of the ARCinformation is implicit through the activation of the relevant parameterset. For example, when a video coding technology or standardcontemplates only picture-based ARC, then a picture parameter set orequivalent may be appropriate.

in the same or another embodiment, ARC reference information (513) maybe present in a Tile Group header (514) or a similar data structure.That reference information (513) can refer to a subset of ARCinformation (515) available in a parameter set (516) with a scope beyonda single picture, for example a sequence parameter set, or decoderparameter set.

The additional level of indirection implied activation of a PPS from atile group header, PPS, SPS, as used in JVET-M0135-v1 appears to beunnecessary according to exemplary embodiments, as picture parametersets, just as sequence parameter sets, can (and have in certainstandards such as RFC3984) be used for capability negotiation orannouncements. If, however, the ARC information should be applicable toa sub picture represented, for example, by a tile groups also, aparameter set with an activation scope limited to a tile group, such asthe Adaptation Parameter set or a Header Parameter Set may be the betterchoice. Also, if the ARC information is of more than negligible size—forexample contains filter control information such as numerous filtercoefficients—then a parameter may be a better choice than using a header(508) directly from a coding efficiency viewpoint, as those settings maybe reusable by future pictures or sub-pictures by referencing the sameparameter set according to exemplary embodiments.

When using the sequence parameter set or another higher parameter setwith a scope spanning multiple pictures, certain considerations mayapply:

-   -   1. The parameter set to store the ARC information table (516)        can, in some cases, be the sequence parameter set, but in other        cases advantageously the decoder parameter set. The decoder        parameter set can have an activation scope of multiple CVSs,        namely the coded video stream, i.e. all coded video bits from        session start until session teardown. Such a scope may be more        appropriate because possible ARC factors may be a decoder        feature, possibly implemented in hardware, and hardware features        tend not to change with any CVS (which in at least some        entertainment systems is a Group of Pictures, one second or less        in length). That said, putting the table into the sequence        parameter set is expressly included in the placement options        described herein, in particular in conjunction with point 2        below.    -   2. The ARC reference information (513) may advantageously be        placed directly into the picture/slice tile/GOB/tile group        header (tile group header henceforth) (514) rather than into the        picture parameter set as in JVCET-M0135-v1, The reason is as        follows: when an encoder wants to change a single value in a        picture parameter set, such as for example the ARC reference        information, then it has to create a new PPS and reference that        new PPS. Assume that only the ARC reference information changes,        but other information such as, for example, the quantization        matrix information in the PPS stays. Such information can be of        substantial size, and would need to be retransmitted to make the        new PPS complete. As the ARC reference information may be a        single codeword, such as the index into the table (513) and that        would be the only value that changes, it would be cumbersome and        wasteful to retransmit all the, for example, quantization matrix        information. Insofar, can be considerably better from a coding        efficiency viewpoint to avoid the indirection through the PPS,        as proposed in JVET-M0135-v1. Similarly, putting the ARC        reference information into the PPS has the additional        disadvantage that the ARC information referenced by the ARC        reference information (513) necessarily needs to apply to the        whole picture and not to a sub-picture, as the scope of a        picture parameter set activation is a picture.

In the same and other embodiments, the signaling of ARC parameters canfollow a detailed example as outlined in FIG. 6. FIG. 6 depicts syntaxdiagrams in a representation (600) as used in video coding standards.The notation of such syntax diagrams roughly follows C-styleprogramming. Lines in boldface indicate syntax elements present in thebitstream, lines without boldface often indicate control flow or thesetting of variables.

A tile group header (601) as an exemplary syntax structure of a headerapplicable to a (possibly rectangular) part of a picture canconditionally contain, a variable length, Exp-Golomb coded syntaxelement dec_pic_size_idx (602) (depicted in boldface). The presence ofthis syntax element in the tile group header can be gated on the use ofadaptive resolution (603)—here, the value of a flag not depicted inboldface, which means that flag is present in the bitstream at the pointwhere it occurs in the syntax diagram. Whether or not adaptiveresolution is in use for this picture or parts thereof can be signaledin any high level syntax structure inside or outside the bitstream. Inthe example shown, it is signaled in the sequence parameter set asoutlined below.

Still referring to FIG. 6, shown is also an excerpt of a sequenceparameter set (610). The first syntax element shown isadaptive_pic_resolution_change_flag (611). When true, that flag canindicate the use of adaptive resolution which, in turn may requirecertain control information. In the example, such control information isconditionally present based on the value of the flag based on the if( )statement in the parameter set (612) and the tile group header (601).

When adaptive resolution is in use, according to exemplary embodiments,coded is an output resolution in units of samples (613). The numeral 613refers to both output_pic_width_in_luma_samples andoutput_pic_height_in_luma_samples, which together can define theresolution of the output picture. Elsewhere in a video coding technologyor standard, certain restrictions to either value can be defined. Forexample, a level definition may limit the number of total outputsamples, which could be the product of the value of those two syntaxelements. Also, certain video coding technologies or standards, orexternal technologies or standards such as, for example, systemstandards, may limit the numbering range (for example, one or bothdimensions must be divisible by a power of 2 number), or the aspectratio (for example, the width and height must be in a relation such as4:3 or 16:9). Such restrictions may be introduced to facilitate hardwareimplementations or for other reasons.

In certain applications, it can be advisable that the encoder instructsthe decoder to use a certain reference picture size rather thanimplicitly assume that size to be the output picture size. In thisexample, the syntax element reference_pic_size_present_flag (614) gatesthe conditional presence of reference picture dimensions (615) (again,the numeral refers to both width and height).

Finally, shown is a table of possible decoding picture width andheights. Such a table can be expressed, for example, by a tableindication (num_dec_pic_size_in_luma_samples_minus1) (616). The “minus1”can refer to the interpretation of the value of that syntax element. Forexample, if the coded value is zero, one table entry is present. If thevalue is five, six table entries are present. For each “line” in thetable, decoded picture width and height are then included in the syntax(617).

The table entries presented (617) can be indexed using the syntaxelement dec_pic_size_idx (602) in the tile group header, therebyallowing different decoded sizes—in effect, zoom factors—per tile group.

Certain video coding technologies or standards, for example VP9, supportspatial scalability by implementing certain forms of reference pictureresampling (signaled quite differently from the disclosed subjectmatter) in conjunction with temporal scalability, so to enable spatialscalability. In particular, certain reference pictures may be upsampledusing ARC-style technologies to a higher resolution to form the base ofa spatial enhancement layer. Those upsampled pictures could be refined,using normal prediction mechanisms at the high resolution, so to adddetail.

The disclosed subject matter can be used in such an environment. Incertain cases, in the same and other embodiments, a value in the NALunit header, for example the Temporal ID field, can be used to indicatenot only the temporal but also the spatial layer. Doing so has certainadvantages for certain system designs; for example, existing SelectedForwarding Units (SFU) created and optimized for temporal layer selectedforwarding based on the NAL unit header Temporal ID value can be usedwithout modification, for scalable environments. In order to enablethat, there may be a requirement for a mapping between the coded picturesize and the temporal layer is indicated by the temporal ID field in theNAL unit header.

In some video coding technologies, an Access Unit (AU) can refer tocoded picture(s), slice(s), tile(s), NAL Unit(s), and so forth, thatwere captured and composed into a the respective picture/slice/tile/NALunit bitstream at a given instance in time. That instance in time can bethe composition time.

In HEVC, and certain other video coding technologies, a picture ordercount (POC) value can be used for indicating a selected referencepicture among multiple reference picture stored in a decoded picturebuffer (DPB). When an access unit (AU) comprises one or more pictures,slices, or tiles, each picture, slice, or tile belonging to the same AUmay carry the same POC value, from which it can be derived that theywere created from content of the same composition time. In other words,in a scenario where two pictures/slices/tiles carry the same given POCvalue, that can be indicative of the two picture/slice/tile belonging tothe same AU and having the same composition time. Conversely, twopictures/tiles/slices having different POC values can indicate thosepictures/slices/tiles belonging to different AUs and having differentcomposition times.

According to exemplary embodiments of the disclosed subject matter,aforementioned rigid relationship can be relaxed in that an access unitcan comprise pictures, slices, or tiles with different POC values. Byallowing different POC values within an AU, it becomes possible to usethe POC value to identify potentially independently decodablepictures/slices/tiles with identical presentation time. That, in turn,can enable support of multiple scalable layers without a change ofreference picture selection signaling (e.g. reference picture setsignaling or reference picture list signaling), as described in moredetail below.

It is, however, still desirable to be able to identify the AU that apicture/slice/tile belongs to, with respect to otherpicture/slices/tiles having different POC values, from the POC valuealone. This can be achieved, as described below.

In the same and other embodiments, an access unit count (AUC) may besignaled in a high-level syntax structure, such as NAL unit header,slice header, tile group header, SEI message, parameter set or AUdelimiter. The value of AUC may be used to identify which NAL units,pictures, slices, or tiles belong to a given AU. The value of AUC may becorresponding to a distinct composition time instance. The AUC value maybe equal to a multiple of the POC value. By dividing the POC value by aninteger value, the AUC value may be calculated. In certain cases,division operations can place a certain burden on decoderimplementations. In such cases, small restrictions in the numberingspace of the AUC values may allow to substitute the division operationby shift operations. For example, the AUC value may be equal to a MostSignificant Bit (MSB) value of the POC value range.

In the same and other embodiments, a value of picture order count (POC)cycle per AU (poc_cycle_au) may be signaled in a high-level syntaxstructure, such as NAL unit header, slice header, tile group header, SEImessage, parameter set or AU delimiter. The poc_cycle_au may indicatehow many different and consecutive POC values can be associated with thesame AU. For example, if the value of poc_cycle_au is equal to 4, thepictures, slices or tiles with the POC value equal to 0-3, inclusive,are associated with the AU with AUC value equal to 0, and the pictures,slices or tiles with POC value equal to 4-7, inclusive, are associatedwith the AU with AUC value equal to 1. Hence, the value of AUC may beinferred by dividing the POC value by the value of poc_cycle_au.

In the same and other embodiments, the value of poc_cycle_au may bederived from information, located for example in the video parameter set(VPS), that identifies the number of spatial or SNR layers in a codedvideo sequence. Such a possible relationship is briefly described below.While the derivation as described above may save a few bits in the VPSand hence may improves coding efficiency, it can be advantageous toexplicitly code poc_cycle_au in an appropriate high level syntaxstructure hierarchically below the video parameter set, so to be able tominimize poc_cycle_au for a given small part of a bitstream such as apicture. This optimization may save more bits than can be saved throughthe derivation process above because POC values (and/or values of syntaxelements indirectly referring to POC) may be coded in low level syntaxstructures.

In the same or another embodiment, FIG. 9 shows an example (900) ofsyntax tables to signal the syntax element of vps_poc_cycle_au in VPS(or SPS), which indicates the poc_cycle_au used for all picture/slicesin a coded video sequence, and the syntax element of slice_poc_cycle_au,which indicates the poc_cycle_au of the current slice, in slice header.If the POC value increases uniformly per AU,vps_contant_poc_cycle_per_au in VPS is set equal to 1 andvps_poc_cycle_au is signaled in VPS. In this case, slice_poc_cycle_au isnot explicitly signaled, and the value of AUC for each AU is calculatedby dividing the value of POC by vps_poc_cycle_au. If the POC value doesnot increase uniformly per AU, vps_contant_poc_cycle_per_au in VPS isset equal to 0. In this case, vps_access_unit_cnt is not signaled, whileslice_access_unit_cnt is signaled in slice header for each slice orpicture. Each slice or picture may have a different value ofslice_access_unit_cnt. The value of AUC for each AU is calculated bydividing the value of POC by slice_poc_cycle_au. FIG. 10 shows a blockdiagram illustrating the relevant work flow (1000) in which at S100there is considered parsing VPS/SPS and identifying whether the POCcycle per AU is constant or not, and at S101 a POC cycle per AU constantwithin a coded video sequence is determined. If not, then at S103 thereis calculating the value of the access unit count from picture levelpoc_cycle au value and POC value, and if so at S102 there is calculatingthe value of the access unit count from sequence levelpoc_cycle_au_value and POC value. At S104, there is again consideredparsing VPS/SPS and identifying whether the POC cycle per AU is constantor not which may continue cyclically or otherwise one or more portionsof the work flow (1000).

In the same and other embodiments, even though the value of POC of apicture, slice, or tile may be different, the picture, slice, or tilecorresponding to an AU with the same AUC value may be associated withthe same decoding or output time instance. Hence, without anyinter-parsing/decoding dependency across pictures, slices or tiles inthe same AU, all or subset of pictures, slices or tiles associated withthe same AU may be decoded in parallel, and may be outputted at the sametime instance.

In the same and other embodiments, even though the value of POC of apicture, slice, or tile may be different, the picture, slice, or tilecorresponding to an AU with the same AUC value may be associated withthe same composition/display time instance. When the composition time iscontained in a container format, even though pictures correspond todifferent AUs, if the pictures have the same composition time, thepictures can be displayed at the same time instance.

In the same and other embodiments, each picture, slice, or tile may havethe same temporal identifier (temporal_id) in the same AU. All or subsetof pictures, slices or tiles corresponding to a time instance may beassociated with the same temporal sub-layer. In the same and otherembodiments, each picture, slice, or tile may have the same or adifferent spatial layer id (layer_id) in the same AU. All or subset ofpictures, slices or tiles corresponding to a time instance may beassociated with the same or a different spatial layer.

FIG. 8 shows an example (800) of a video sequence structure withcombination of temporal_id, layer_id, POC and AUC values with adaptiveresolution change. In this example, a picture, slice or tile in thefirst AU with AUC=0 may have temporal_id=0 and layer_id=0 or 1, while apicture, slice or tile in the second AU with AUC=1 may havetemporal_id=1 and layer_id=0 or 1, respectively. The value of POC isincreased by 1 per picture regardless of the values of temporal_id andlayer_id. In this example, the value of poc_cycle_au can be equal to 2.Preferably, the value of poc_cycle_au may be set equal to the number of(spatial scalability) layers. In this example, hence, the value of POCis increased by 2, while the value of AUC is increased by 1.

In exemplary embodiments, all or sub-set of inter-picture or inter-layerprediction structure and reference picture indication may be supportedby using the existing reference picture set (RPS) signaling in HEVC orthe reference picture list (RPL) signaling. In RPS or RPL, the selectedreference picture is indicated by signaling the value of POC or thedelta value of POC between the current picture and the selectedreference picture. For the disclosed subject matter, the RPS and RPL canbe used to indicate the inter-picture or inter-layer predictionstructure without change of signaling, but with the followingrestrictions. If the value of temporal_id of a reference picture isgreater than the value of temporal_id current picture, the currentpicture may not use the reference picture for motion compensation orother predictions. If the value of layer_id of a reference picture isgreater than the value of layer_id current picture, the current picturemay not use the reference picture for motion compensation or otherpredictions.

In the same and other embodiments, the motion vector scaling based onPOC difference for temporal motion vector prediction may be disabledacross multiple pictures within an access unit. Hence, although eachpicture may have a different POC value within an access unit, the motionvector is not scaled and used for temporal motion vector predictionwithin an access unit. This is because a reference picture with adifferent POC in the same AU is considered a reference picture havingthe same time instance. Therefore, in exemplary embodiments, the motionvector scaling function may return 1, when the reference picture belongsto the AU associated with the current picture.

In the same and other embodiments, the motion vector scaling based onPOC difference for temporal motion vector prediction may be optionallydisabled across multiple pictures, when the spatial resolution of thereference picture is different from the spatial resolution of thecurrent picture. When the motion vector scaling is allowed, the motionvector is scaled based on both POC difference and the spatial resolutionratio between the current picture and the reference picture.

In the same or another embodiment, the motion vector may be scaled basedon AUC difference instead of POC difference, for temporal motion vectorprediction, especially when the poc_cycle_au has non-uniform value (whenvps_contant_poc_cycle_per_au==0). Otherwise (whenvps_contant_poc_cycle_per_au==1), the motion vector scaling based on AUCdifference may be identical to the motion vector scaling based on POCdifference.

In the same or another embodiment, when the motion vector is scaledbased on AUC difference, the reference motion vector in the same AU(with the same AUC value) with the current picture is not scaled basedon AUC difference and used for motion vector prediction without scalingor with scaling based on spatial resolution ratio between the currentpicture and the reference picture.

In the same and other embodiments, the AUC value is used for identifyingthe boundary of AU and used for hypothetical reference decoder (HRD)operation, which needs input and output timing with AU granularity. Inmost cases, the decoded picture with the highest layer in an AU may beoutputted for display. The AUC value and the layer_id value can be usedfor identifying the output picture.

In exemplary embodiments, a picture may consist of one or moresub-pictures. Each sub-picture may cover a local region or the entireregion of the picture. The region supported by a sub-picture may or maynot be overlapped with the region supported by another sub-picture. Theregion composed by one or more sub-pictures may or may not cover theentire region of a picture. If a picture consists of a sub-picture, theregion supported by the sub-picture is identical to the region supportedby the picture.

In the same and other embodiments, a sub-picture may be coded by acoding method similar to the coding method used for the coded picture. Asub-picture may be independently coded or may be coded dependent onanother sub-picture or a coded picture. A sub-picture may or may nothave any parsing dependency from another sub-picture or a coded picture.

In the same and other embodiments, a coded sub-picture may be containedin one or more layers. A coded sub-picture in a layer may have adifferent spatial resolution. The original sub-picture may be spatiallyre-sampled (up-sampled or down-sampled), coded with different spatialresolution parameters, and contained in a bitstream corresponding to alayer.

In the same and other embodiments, a sub-picture with (W, H), where Windicates the width of the sub-picture and H indicates the height of thesub-picture, respectively, may be coded and contained in the codedbitstream corresponding to layer 0, while the up-sampled (ordown-sampled) sub-picture from the sub-picture with the original spatialresolution, with (W*S_(w,k), H*S_(h,k)), may be coded and contained inthe coded bitstream corresponding to layer k, where S_(w,k), S_(h,k)indicate the resampling ratios, horizontally and vertically. If thevalues of S_(w,k), S_(h,k) are greater than 1, the resampling is equalto the up-sampling. Whereas, if the values of S_(w,k), S_(h,k) aresmaller than 1, the resampling is equal to the down-sampling.

In the same and other embodiments, a coded sub-picture in a layer mayhave a different visual quality from that of the coded sub-picture inanother layer in the same sub-picture or different subpicture. Forexample, sub-picture i in a layer, n, is coded with the quantizationparameter, while a sub-picture j in a layer, m, is coded with thequantization parameter, Q_(j,m).

In the same and other embodiments, a coded sub-picture in a layer may beindependently decodable, without any parsing or decoding dependency froma coded sub-picture in another layer of the same local region. Thesub-picture layer, which can be independently decodable withoutreferencing another sub-picture layer of the same local region, is theindependent sub-picture layer. A coded sub-picture in the independentsub-picture layer may or may not have a decoding or parsing dependencyfrom a previously coded sub-picture in the same sub-picture layer, butthe coded sub-picture may not have any dependency from a coded picturein another sub-picture layer.

In the same and other embodiments, a coded sub-picture in a layer may bedependently decodable, with any parsing or decoding dependency from acoded sub-picture in another layer of the same local region. Thesub-picture layer, which can be dependently decodable with referencinganother sub-picture layer of the same local region, is the dependentsub-picture layer. A coded sub-picture in the dependent sub-picture mayreference a coded sub-picture belonging to the same sub-picture, apreviously coded sub-picture in the same sub-picture layer, or bothreference sub-pictures.

In the same and other embodiments, a coded sub-picture consists of oneor more independent sub-picture layers and one or more dependentsub-picture layers. However, at least one independent sub-picture layermay be present for a coded sub-picture. The independent sub-picturelayer may have the value of the layer identifier (layer_id), which maybe present in NAL unit header or another high-level syntax structure,equal to 0. The sub-picture layer with the layer_id equal to 0 is thebase sub-picture layer.

In the same and other embodiments, a picture may consist of one or moreforeground sub-pictures and one background sub-picture. The regionsupported by a background sub-picture may be equal to the region of thepicture. The region supported by a foreground sub-picture may beoverlapped with the region supported by a background sub-picture. Thebackground sub-picture may be a base sub-picture layer, while theforeground sub-picture may be a non-base (enhancement) sub-picturelayer. One or more non-base sub-picture layer may reference the samebase layer for decoding. Each non-base sub-picture layer with layer_idequal to a may reference a non-base sub-picture layer with layer_idequal to b, where a is greater than b.

In the same or another embodiment, a picture may consist of one or moreforeground sub-pictures with or without a background sub-picture. Eachsub-picture may have its own base sub-picture layer and one or morenon-base (enhancement) layers. Each base sub-picture layer may bereferenced by one or more non-base sub-picture layers. Each non-basesub-picture layer with layer_id equal to a may reference a non-basesub-picture layer with layer_id equal to b, where a is greater than b.

In the same and other embodiments, a picture may consist of one or moreforeground sub-pictures with or without a background sub-picture. Eachcoded sub-picture in a (base or non-base) sub-picture layer may bereferenced by one or more non-base layer sub-pictures belonging to thesame sub-picture and one or more non-base layer sub-pictures, which arenot belonging to the same sub-picture.

In the same and other embodiments, a picture may consist of one or moreforeground sub-pictures with or without a background sub-picture. Asub-picture in a layer a may be further partitioned into multiplesub-pictures in the same layer. One or more coded sub-pictures in alayer b may reference the partitioned sub-picture in a layer a.

In the same and other embodiments, a coded video sequence (CVS) may be agroup of the coded pictures. The CVS may consist of one or more codedsub-picture sequences (CSPS), where the CSPS may be a group of codedsub-pictures covering the same local region of the picture. A CSPS mayhave the same or a different temporal resolution than that of the codedvideo sequence.

In the same and other embodiments, a CSPS may be coded and contained inone or more layers. A CSPS may consist of one or more CSPS layers.Decoding one or more CSPS layers corresponding to a CSPS may reconstructa sequence of sub-pictures corresponding to the same local region.

In the same and other embodiments, the number of CSPS layerscorresponding to a CSPS may be identical to or different from the numberof CSPS layers corresponding to another CSPS.

In the same or another embodiment, a CSPS layer may have a differenttemporal resolution (e.g. frame rate) from another CSPS layer. Theoriginal (uncompressed) sub-picture sequence may be temporallyre-sampled (up-sampled or down-sampled), coded with different temporalresolution parameters, and contained in a bitstream corresponding to alayer.

In the same or another embodiment, a sub-picture sequence with the framerate, F, may be coded and contained in the coded bitstream correspondingto layer 0, while the temporally up-sampled (or down-sampled)sub-picture sequence from the original sub-picture sequence, withF*S_(t,k), may be coded and contained in the coded bitstreamcorresponding to layer k, where S_(t,k) indicates the temporal samplingratio for layer k. If the value of S_(t,k) is greater than 1, thetemporal resampling process is equal to the frame rate up conversion.Whereas, if the value of S_(t,k) is smaller than 1, the temporalresampling process is equal to the frame rate down conversion.

In the same and other embodiments, when a sub-picture with a CSPS layera is reference by a sub-picture with a CSPS layer b for motioncompensation or any inter-layer prediction, if the spatial resolution ofthe CSPS layer a is different from the spatial resolution of the CSPSlayer b, decoded pixels in the CSPS layer a are resampled and used forreference. The resampling process may need an up-sampling filtering or adown-sampling filtering.

FIG. 11 shows an example video stream (1100) including a backgroundvideo CSPS with layer_id equal to 0 and multiple foreground CSPS layers.While a coded sub-picture may consist of one or more CSPS layers, abackground region, which does not belong to any foreground CSPS layer,may consist of a base layer. The base layer may contain a backgroundregion and foreground regions, while an enhancement CSPS layer contain aforeground region. An enhancement CSPS layer may have a better visualquality than the base layer, at the same region. The enhancement CSPSlayer may reference the reconstructed pixels and the motion vectors ofthe base layer, corresponding to the same region.

In the same and other embodiments, the video bitstream corresponding toa base layer is contained in a track, while the CSPS layerscorresponding to each sub-picture are contained in a separated track, ina video file.

In the same and other embodiments, the video bitstream corresponding toa base layer is contained in a track, while CSPS layers with the samelayer_id are contained in a separated track. In this example, a trackcorresponding to a layer k includes CSPS layers corresponding to thelayer k, only.

In the same and other embodiments, each CSPS layer of each sub-pictureis stored in a separate track. Each trach may or may not have anyparsing or decoding dependency from one or more other tracks.

In the same and other embodiments, each track may contain bitstreamscorresponding to layer i to layer j of CSPS layers of all or a subset ofsub-pictures, where 0<i=<j=<k, k being the highest layer of CSPS.

In the same and other embodiments, a picture consists of one or moreassociated media data including depth map, alpha map, 3D geometry data,occupancy map, etc. Such associated timed media data can be divided toone or multiple data sub-stream each of which corresponding to onesub-picture.

In the same and other embodiments, FIG. 12 shows an example of videoconference (1200) based on the multi-layered sub-picture method. In avideo stream, one base layer video bitstream corresponding to thebackground picture and one or more enhancement layer video bitstreamscorresponding to foreground sub-pictures are contained. Each enhancementlayer video bitstream is corresponding to a CSPS layer. In a display,the picture corresponding to the base layer is displayed by default. Itcontains one or more user's picture in a picture (PIP). When a specificuser is selected by a client's control, the enhancement CSPS layercorresponding to the selected user is decoded and displayed with theenhanced quality or spatial resolution. FIG. 13 shows the diagram (1300)for the operation in which at S130 there is a decoding of the videobitstream with the multi-layers, and at S131 there is an identificationof the background region and one or more foreground subpictures. At S132it is determined if a specific sub-picture region is selection. If not,then at S134 there is a decoding and display of the background region,and if so, then at S133 there is a decoding and display of the enhancedsub-picture, and the diagram (1300) may continue cyclically from thereor may proceed in sequence or parallel with other operations.

In the same and other embodiments, a network middle box (such as router)may select a subset of layers to send to a user depending on itsbandwidth. The picture/subpicture organization may be used for bandwidthadaptation. For instance, if the user doesn't have the bandwidth, therouter strips of layers or selects some subpictures due to theirimportance or based on used setup and this can be done dynamically toadopt to bandwidth.

FIG. 14 shows a use case (1400) of 360 video. When a spherical 360picture is projected onto a planar picture, the projection 360 picturemay be partitioned into multiple sub-pictures as a base layer. Anenhancement layer of a specific sub-picture may be coded and transmittedto a client. A decoder may be able to decode both the base layerincluding all sub-pictures and an enhancement layer of a selectedsub-picture. When the current viewport is identical to the selectedsub-picture, the displayed picture may have a higher quality with thedecoded sub-picture with the enhancement layer. Otherwise, the decodedpicture with the base layer can be displayed, with a low quality.

In the same and other embodiments, any layout information for displaymay be present in a file, as supplementary information (such as SEImessage or metadata). One or more decoded sub-pictures may be relocatedand displayed depending on the signaled layout information. The layoutinformation may be signaled by a streaming server or a broadcaster, ormay be regenerated by a network entity or a cloud server, or may bedetermined by a user's customized setting.

In exemplary embodiments, when an input picture is divided into one ormore (rectangular) sub-region(s), each sub-region may be coded as anindependent layer. Each independent layer corresponding to a localregion may have a unique layer_id value. For each independent layer, thesub-picture size and location information may be signaled. For example,picture size (width, height), the offset information of the left-topcorner (x_offset, y_offset). FIG. 15 shows an example (1500) of thelayout of divided sub-pictures, its sub-picture size and positioninformation and its corresponding picture prediction structure. Thelayout information including the sub-picture size(s) and the sub-pictureposition(s) may be signaled in a high-level syntax structure, such asparameter set(s), header of slice or tile group, or SEI message.

In the same and other embodiments, each sub-picture corresponding to anindependent layer may have its unique POC value within an AU. When areference picture among pictures stored in DPB is indicated by usingsyntax element(s) in RPS or RPL structure, the POC value(s) of eachsub-picture corresponding to a layer may be used.

In the same and other embodiments, in order to indicate the(inter-layer) prediction structure, the layer_id may not be used and thePOC (delta) value may be used.

In the same and other embodiments, a sub-picture with a POC vale equalto N corresponding to a layer (or a local region) may or may not be usedas a reference picture of a sub-picture with a POC value equal to N+K,corresponding to the same layer (or the same local region) for motioncompensated prediction. In most cases, the value of the number K may beequal to the maximum number of (independent) layers, which may beidentical to the number of sub-regions.

In the same and other embodiments, FIG. 16 shows the extended case(1600) of FIG. 15. When an input picture is divided into multiple (e.g.four) sub-regions, each local region may be coded with one or morelayers. In the case, the number of independent layers may be equal tothe number of sub-regions, and one or more layers may correspond to asub-region. Thus, each sub-region may be coded with one or moreindependent layer(s) and zero or more dependent layer(s).

In the same and other embodiments, in FIG. 16, the input picture may bedivided into four sub-regions. The right-top sub-region may be coded astwo layers, which are layer 1 and layer 4, while the right-bottomsub-region may be coded as two layers, which are layer 3 and layer 5. Inthis case, the layer 4 may reference the layer 1 for motion compensatedprediction, while the layer 5 may reference the layer 3 for motioncompensation.

In the same and other embodiments, in-loop filtering (such as deblockingfiltering, adaptive in-loop filtering, reshaper, bilateral filtering orany deep-learning based filtering) across layer boundary may be(optionally) disabled.

In the same and other embodiments, motion compensated prediction orintra-block copy across layer boundary may be (optionally) disabled.

In the same and other embodiments, boundary padding for motioncompensated prediction or in-loop filtering at the boundary ofsub-picture may be processed optionally. A flag indicating whether theboundary padding is processed or not may be signaled in a high-levelsyntax structure, such as parameter set(s) (VPS, SPS, PPS, or APS),slice or tile group header, or SEI message.

In the same and other embodiments, the layout information ofsub-region(s) (or sub-picture(s)) may be signaled in VPS or SPS. FIG. 17shows an example (1700) of the syntax elements in VPS and SPS. In thisexample, vps_sub_picture_dividing_flag is signaled in VPS. The flag mayindicate whether input picture(s) are divided into multiple sub-regionsor not. When the value of vps_sub_picture_dividing_flag is equal to 0,the input picture(s) in the coded video sequence(s) corresponding to thecurrent VPS may not be divided into multiple sub-regions. In this case,the input picture size may be equal to the coded picture size(pic_width_in_luma_samples, pic_height_in_luma_samples), which issignaled in SPS. When the value of vps_sub_picture_dividing_flag isequal to 1, the input picture(s) may be divided into multiplesub-regions. In this case, the syntax elementsvps_full_pic_width_in_luma_samples andvps_full_pic_height_in_luma_samples are signaled in VPS. The values ofvps_full_pic_width_in_luma_samples andvps_full_pic_height_in_luma_samples may be equal to the width and heightof the input picture(s), respectively.

In the same and other embodiments, the values ofvps_full_pic_width_in_luma_samples andvps_full_pic_height_in_luma_samples may not be used for decoding, butmay be used for composition and display.

In the same and other embodiments, when the value ofvps_sub_picture_dividing_flag is equal to 1, the syntax elementspic_offset_x and pic_offset_y may be signaled in SPS, which correspondsto (a) specific layer(s). In this case, the coded picture size(pic_width_in_luma_samples, pic_height_in_luma_samples) signaled in SPSmay be equal to the width and height of the sub-region corresponding toa specific layer. Also, the position (pic_offset_x, pic_offset_y) of theleft-top corner of the sub-region may be signaled in SPS.

In the same and other embodiments, the position information(pic_offset_x, pic_offset_y) of the left-top corner of the sub-regionmay not be used for decoding, but may be used for composition anddisplay.

In the same or another embodiment, the layout information (size andposition) of all or sub-set sub-region(s) of (an) input picture(s), thedependency information between layer(s) may be signaled in a parameterset or an SEI message. FIG. 18 shows an example (1800) of syntaxelements to indicate the information of the layout of sub-regions, thedependency between layers, and the relation between a sub-region and oneor more layers. In this example (1800), the syntax elementnum_sub_region indicates the number of (rectangular) sub-regions in thecurrent coded video sequence. the syntax element num_layers indicatesthe number of layers in the current coded video sequence. The value ofnum_layers may be equal to or greater than the value of num_sub_region.When any sub-region is coded as a single layer, the value of num_layersmay be equal to the value of num_sub_region. When one or moresub-regions are coded as multiple layers, the value of num_layers may begreater than the value of num_sub_region. The syntax element directdependency flag[i][j] indicates the dependency from the j-th layer tothe i-th layer. num_layers_for_region[i] indicates the number of layersassociated with the i-th sub-region. sub_region_layer_id[i][j] indicatesthe layer_id of the j-th layer associated with the i-th sub-region. Thesub_region_offset_x[i] and sub_region_offset_y[i] indicate thehorizontal and vertical location of the left-top corner of the i-thsub-region, respectively. The sub_region_width [i] andsub_region_height[i] indicate the width and height of the i-thsub-region, respectively.

In one embodiment, one or more syntax elements that specify the outputlayer set to indicate one of more layers to be outputted with or withoutprofile tier level information may be signaled in a high-level syntaxstructure, e.g. VPS, DPS, SPS, PPS, APS or SEI message. Referring to theexample (1900) in FIG. 19, the syntax element num_output_layer_setsindicating the number of output layer set (OLS) in the coded videsequence referring to the VPS may be signaled in the VPS. For eachoutput layer set, output_layer_flag may be signaled as many as thenumber of output layers.

In the same and other embodiments, output_layer_flag[i] equal to 1specifies that the i-th layer is output. vps_output_layer_flag[i] equalto 0 specifies that the i-th layer is not output.

In the same and other embodiments, one or more syntax elements thatspecify the profile tier level information for each output layer set maybe signaled in a high-level syntax structure, e.g. VPS, DPS, SPS, PPS,APS or SEI message. Still referring to FIG. 19, the syntax elementnum_profile_tile_level indicating the number of profile tier levelinformation per OLS in the coded vide sequence referring to the VPS maybe signaled in the VPS. For each output layer set, a set of syntaxelements for profile tier level information or an index indicating aspecific profile tier level information among entries in the profiletier level information may be signaled as many as the number of outputlayers.

In the same and other embodiments, profile_tier_level_idx[i][j]specifies the index, into the list of profile_tier_level( ) syntaxstructures in the VPS, of the profile_tier_level( ) syntax structurethat applies to the j-th layer of the i-th OLS.

In the same and other embodiments, referring to the example (2000) ofFIG. 20, the syntax elements num_profile_tile_level and/ornum_output_layer_sets may be signaled when the number of maximum layersis greater than 1 (vps_max_layers_minus1>0).

In the same and other embodiments, referring to FIG. 20, the syntaxelement vps_output_layers_mode[i] indicating the mode of output layersignaling for the i-th output layer set may be present in VPS.

In the same and other embodiments, vps_output_layers_mode[i] equal to 0specifies that only the highest layer is output with the i-th outputlayer set. vps_output_layer_mode[i] equal to 1 specifies that all layersare output with the i-th output layer set. vps_output_layer_mode[i]equal to 2 specifies that the layers that are output are the layers withvps_output_layer_flag[i][j] equal to 1 with the i-th output layer set.More values may be reserved according to embodiments.

In the same and other embodiments, the output_layer_flag[i][j] may ormay not be signaled depending on the value of vps_output_layers_mode[i]for the i-th output layer set.

In the same and other embodiments, referring to FIG. 20, the flagvps_ptl_signal_flag[i] may be present for the i-th output layer set.Depending the value of vps_ptl_signal_flag[i], the profile tier levelinformation for the i-th output layer set may or may not be signaled.

In the same and other embodiments, referring to FIG. 21, the number ofsubpicture, max_subpics_minus1, in the current CVS may be signalled in ahigh-level syntax structure, e.g. VPS, DPS, SPS, PPS, APS or SEImessage.

In the same and other embodiments, referring to FIG. 21, the subpictureidentifier, sub_pic_id[i], for the i-th subpicture may be signalled,when the number of subpictures is greater than 1 (max_subpics_minus1>0).

In the same and other embodiments, one or more syntax elementsindicating the subpicture identifier belonging to each layer of eachoutput layer set may be signalled in VPS. Referring to FIG. 21, thesub_pic_id_layer[i][j][k], which indicates the k-th subpicture presentin the j-th layer of the i-th output layer set. With those information,a decoder may recognize which sub-picture may be decoded and outputtedfor each layer of a specific output layer set.

In the same and other embodiments, the following syntax elements may beused for defining the layout of sub-pictures across layers or in asingle layer. The output layer sets with sub-picture partitioning may besignaled with profile/tier/layer information in VPS or SPS. In PPS, theupdated layout information of subpicture may be present, when thepicture size is updated by the reference picture resampling. For VPS,Table 2 may be considered:

TABLE 2 Descriptor video_parameter_set_rbsp( ) { ... vps _(—) max _(—)layers _(—) minus1 u(6) if( vps_max_layers_minus1 > 0 ) vps _(—) all_(—) independent _(—) layers _(—) flag u(1) for( i = 0; i <=vps_max_layers_minus1; i++ ) { vps _(—) layer _(—) id[ i ] u(6) if( i >0 && !vps_all_independent_layers_flag ) { vps _(—) independent _(—)layer _(—) flag[ i ] u(1) if( !vps_independent_layer_flag[ i ] ) for( j= 0; j < i; j++ ) vps _(—) direct _(—) dependency _(—) flag[ i ][ j ]u(1) } } vps _(—) sub _(—) picture _(—) info _(—) present _(—) flag u(1)if( vps_sub_picture_info_present_flag ) { vps _(—) sub _(—) pic _(—) id_(—) present _(—) flag u(1) if( vps_sub_pic_id_present_flag ) vps _(—)sub _(—) pic _(—) id _(—) length _(—) minus1 ue(v) for( i = 0; i <=vps_max_layers_minus1; i++ ) { vps _(—) pic _(—) width _(—) max _(—) in_(—) luma _(—) samples[ i ] ue(v) vps _(—) pic _(—) height _(—) max _(—)in _(—) luma _(—) samples[ i ] ue(v) vps _(—) num _(—) sub _(—) pic _(—)in _(—) pic _(—) minus1[ i ] ue(v) for( j = 0; j <=vps_num_sub_pic_in_pic_minus1[ i ]; j++) { if(vps_sub_pic_id_present_flag ) vps _(—) sub _(—) pic _(—) id[ i ][ j ]u(v) if( j > 0 ) { vps _(—) sub _(—) pic _(—) offset _(—) x _(—) in _(—)luma _(—) samples[ i ][ j ] ue(v) vps _(—) sub _(—) pic _(—) offset _(—)y _(—) in _(—) luma _(—) samples[ i ][ j ] ue(v) } vps _(—) sub _(—) pic_(—) width _(—) in _(—) luma _(—) samples[ i ][ j ] ue(v) vps _(—) sub_(—) pic _(—) height _(—) in _(—) luma _(—) samples[ i ][ j ] ue(v) } }} if(vps_max_layers_minus1 > 0) { vps _(—) num _(—) output _(—) layer_(—) sets _(—) minus1 ue(v) vps _(—) num _(—) profile _(—) tier _(—)level _(—) minus1 ue(v) } for( i = 0; i < num_profile_tier_level; i++ )profile_tier_level( vps_max_sub_layers_minus1 ) for( i = 0; i <num_output_layer_sets; i++ ) { vps _(—) output _(—) layers _(—) mode[ i] u(2) for( j = 0; j < NumLayersInIdList[ i ]; j++ ) { if(vps_sub_picture_info_present_flag ){ vps _(—) num _(—) output _(—)subpic _(—) layer _(—) minus1[i][j] ue(v) for( k = 0; k <num_output_subpic_layer[i][j]; k++ ) vps _(—) sub _(—) pic _(—) id _(—)layer[i][j] [k] u(8) } if(vps_output_layers_mode[ i ] = = 2 ) vps _(—)output _(—) layer _(—) flag[ i ][ j ] u(1) vps _(—) profile _(—) tier_(—) level _(—) idx[ i ][ j ] u(v) } } ... }

According to exemplary embodiments, the Table 2vps_sub_picture_info_present_flag equal to 1 specifies that the syntaxelements indicating sub-picture layout and identifiers are present inVPS. The vps_subpicture_info_present_flag equal to 0 specifies that thesyntax elements indicating sub-picture layout and identifiers are notpresent in VPS.

According to exemplary embodiments, the Table 2vps_sub_pic_id_present_flag equal to 1 specifies that vps_sub_pic_id[i][j] is present in VPS. The vps_sub_pic_id_present_flag equal to 0specifies that vps_sub_pic_id[i][j] is not present in VPS.

According to exemplary embodiments, the Table 2vps_sub_pic_id_length_minus1 plus 1 specifies the number of bits used torepresent the syntax element vps_sub_pic_id[i][j]. The value ofvps_sub_pic_id length_minus1 shall be in the range of 0 to 15,inclusive. When not present, the value of vps_sub_pic_id length_minus1is inferred to be equal to Ceil(Log 2(Max(2,vps_num_sub_pic_in_pic_minus1[i]+1)))−1, for the i-th layer.

According to exemplary embodiments, the Table 2 vps_sub_pic_id[i][j]specifies the subpicture ID of the j-th subpicture of the i-th layer.The length of the vps_sub_pic_id[i][j] syntax element is vps_sub_pic_idlength_minus1+1 bits. When not present, vps_sub_pic_id[i][j] is inferredto be equal to j, for each j in the range of 0 tovps_num_sub_pic_in_pic_minus1[i], inclusive.

According to exemplary embodiments, the Table 2vps_pic_width_max_in_luma_samples[i] specifies the maximum width, inunits of luma samples, of each decoded picture of the i-th layer.pic_width_max_in_luma_samples shall not be equal to 0 and shall be aninteger multiple of MinCbSizeY.

According to exemplary embodiments, the Table 2pic_height_max_in_luma_samples specifies the maximum height, in units ofluma samples, of each decoded picture referring to the SPS.pic_height_max_in_luma_samples shall not be equal to 0 and shall be aninteger multiple of MinCbSizeY.

According to exemplary embodiments, the Table 2vps_sub_pic_offset_x_in_luma_samples[i][j] specifies the horizontaloffset, in units of luma samples, of the top-left corner luma sample ofthe j-th subpicture of the i-th layer relative to the top-left cornerluma sample of the composed picture. When not present, the value ofvps_sub_pic_offset_x_in_luma_samples[i][j] is inferred to be equal to 0.vps_sub_pic_offset_x_in_luma_samples[i][j] shall be an integer multipleof CTB size.

According to exemplary embodiments, the Table 2vps_sub_pic_offset_y_in_luma_samples[i][j] specifies the verticaloffset, in units of luma samples, of the top-left corner luma sample ofthe j-th subpictue of the i-th layer relative to the top-left cornerluma sample of the composed picture. When not present, the value ofvps_sub_pic_offset_y_in_luma_samples[i][j] is inferred to be equal to 0.vps_sub_pic_offset_y_in_luma_samples[i][j] shall be an integer multipleof CTB size.

According to exemplary embodiments, the Table 2vps_sub_pic_width_in_luma_samples[i][j] specifies the width of the j-thsubpicture of the i-th layer in units of luma samples.vps_sub_pic_width_in_luma_samples[i][j] shall be an integer multiple ofCTB size.

According to exemplary embodiments, the Table 2vps_sub_pic_height_in_luma_samples[i][j] specifies the height of thej-th subpictue of the i-th layer in units of luma samples.vps_sub_pic_height_in_luma_samples[i][j] shall be an integer multiple ofCTB size.

According to exemplary embodiments, the Table 2vps_num_output_layer_sets_minus1 plus 1 specifies the number of outputlayer set in the coded vide sequence referring to the VPS. When notpresent, the value of vps_num_output_layer_sets_minus1 is inferred to beequal to 0.

According to exemplary embodiments, the Table 2vps_num_profile_tile_levels_minus1 plus 1 specifies the number ofprofile/tier/level information in the coded vide sequence referring tothe VPS. When not present, the value ofvps_num_profile_tile_levels_minus1 is inferred to be equal to 0.

According to exemplary embodiments, the Table 2vps_output_layers_mode[i] equal to 0 specifies that only the highestlayer is output in the i-th output layer set. vps_output_layer_mode[i]equal to 1 specifies that all layers are output in the i-th output layerset. vps_output_layer_mode[i] equal to 2 specifies that the layers thatare output are the layers with vps_output_layer_flag[i][j] equal to 1 inthe i-th output layer set. The value of vps_output_layers_mode[i] shallbe in the range of 0 to 2, inclusive. The value 3 ofvps_output_layer_mode[i] is reserved for future use by ITU-T|ISO/IEC.

According to exemplary embodiments, the Table 2vps_num_output_subpic_layer_minus1[i][j] specifies the number ofsubpictures of the j-th layer of the i-th output layer set.

According to exemplary embodiments, the Table 2vps_sub_pic_id_layer[i][j] [k] specifies the subpicture ID of the k-thoutput subpicture of the j-th subpicture of the i-th layer. The lengthof vps_sub_pic_id_layer[i][j] [k] syntax element is vps_sub_pic_idlength_minus1+1 bits. When not present, vps_sub_pic_id_layer[i][j] [k]is inferred to be equal to k, for each j in the range of 0 tonum_output_subpic_layer_minus1[i][j], inclusive.

According to exemplary embodiments, the Table 2vps_output_layer_flag[i][j] equal to 1 specifies that the j-th layer ofthe i-th output layer set is output. vps_output_layer_flag[i][j] equalto 0 specifies that the j-th layer of the i-th output layer set is notoutput.

According to exemplary embodiments, the Table 2vps_profile_tier_level_idx[i][j] specifies the index, into the list ofprofile_tier_level( ) syntax structures in the VPS, of theprofile_tier_level( ) syntax structure that applies to the j-th layer ofthe i-th output layer set.

For SPS, Table 3 may be considered:

TABLE 3 Descriptor seq_parameter_set_rbsp( ) { ... pic _(—) width _(—)max _(—) in _(—) luma _(—) samples ue(v) pic _(—) height _(—) max _(—)in _(—) luma _(—) samples ue(v) subpics _(—) present _(—) flag u(1) if(subpics_present_flag ) { sps _(—) sub _(—) pic _(—) id _(—) present _(—)flag u(1) if( sps_sub_pic_id_present_flag ) sps _(—) sub _(—) pic _(—)id _(—) length _(—) minus1 ue(v) sps _(—) num _(—) sub _(—) pic _(—) in_(—) pic _(—) minus1 ue(v) for( i = 0; i <=sps_num_sub_pic_in_pic_minus1; i++) { if( sps_sub_pic_id_present_flag )sps _(—) sub _(—) pic _(—) id[ i ] u(v) if( j > 0 ) { sps _(—) sub _(—)pic _(—) offset _(—) x _(—) in _(—) luma _(—) samples[ i ][ j ] ue(v)sps _(—) sub _(—) pic _(—) offset _(—) y _(—) in _(—) luma _(—) samples[i ][ j ] ue(v) } sps _(—) sub _(—) pic _(—) width _(—) in _(—) luma _(—)samples[ i ][ j ] ue(v) sps _(—) sub _(—) pic _(—) height _(—) in _(—)luma _(—) samples[ i ][ j ] ue(v) } } sps _(—) num _(—) output _(—)subpic _(—) sets _(—) minus1 ue(v) for( i = 0; i <=num_output_subpic_sets_minus1; i++ ) { sps _(—) num _(—) output _(—)subpic _(—) minus1[i] ue(v) for( j = 0; j < num_output_subpic_minus1[i];j++ ) sps _(—) sub _(—) pic _(—) id _(—) oss [i][j] u(8)profile_tier_level( sps_max_sub_layers_minus1 ) u(v) } ... }

According to exemplary embodiments, the Table 3pic_width_max_in_luma_samples specifies the maximum width, in units ofluma samples, of each decoded picture referring to the SPS.pic_width_max_in_luma_samples shall not be equal to 0 and shall be aninteger multiple of MinCbSizeY.

According to exemplary embodiments, the Table 3pic_height_max_in_luma_samples specifies the maximum height, in units ofluma samples, of each decoded picture referring to the SPS.pic_height_max_in_luma_samples shall not be equal to 0 and shall be aninteger multiple of MinCbSizeY.

According to exemplary embodiments, the Table 3 subpics_present_flagequal to 1 indicates that subpicture parameters are present in thepresent in the SPS RBSP syntax. subpics_present_flag equal to 0indicates that subpicture parameters are not present in the present inthe SPS RBSP syntax.

According to exemplary embodiments, when a bitstream is the result of asub-bitstream extraction process and contains only a subset of thesubpictures of the input bitstream to the sub-bitstream extractionprocess, it might be required to set the value of subpics_present_flagequal to 1 in the RBSP of the SPSs

According to exemplary embodiments, the Table 3sps_sub_pic_id_present_flag equal to 1 specifies that sps_subpic_id [i]is present in SPS. sps_sub_pic_id_present_flag equal to 0 specifies thatsps_subpic_id[i] is not present in SPS.

According to exemplary embodiments, the Table 3sps_sub_pic_id_length_minus1 plus 1 specifies the number of bits used torepresent the syntax element sps_subpic_id[i][j]. The value ofsps_subpic_id_length_minus1 shall be in the range of 0 to 15, inclusive.When not present, the value of sps_sub_pic_id_length_minus1 is inferredto be equal to Ceil(Log 2(Max(2, sps_num_sub_pic_in_pic_minus1+1)))−1.

According to exemplary embodiments, the Table 3 sps_sub_pic_id[i]specifies the subpicture ID of the i-th subpicture. The length of thesps_sub_pic_id[i] syntax element is sps_sub_pic_id_length_minus1+1 bits.When not present, sps_sub_pic_id[i] is inferred to be equal to i, foreach i in the range of 0 to sps_num_sub_pic_in_pic_minus1, inclusive.

According to exemplary embodiments, the Table 3sps_sub_pic_offset_x_in_luma_samples[i] specifies the horizontal offset,in units of luma samples, of the top-left corner luma sample of the i-thsubpicture relative to the top-left corner luma sample of the composedpicture. When not present, the value ofsps_sub_pic_offset_x_in_luma_samples[i] is inferred to be equal to 0.sps_sub_pic_offset_x_in_luma_samples[i] shall be an integer multiple ofCTB size.

According to exemplary embodiments, the Table 3sps_sub_pic_offset_y_in_luma_samples[i] specifies the vertical offset,in units of luma samples, of the top-left corner luma sample of the i-thsubpictue relative to the top-left corner luma sample of the composedpicture. When not present, the value ofsps_sub_pic_offset_y_in_luma_samples[i] is inferred to be equal to 0.sps_sub_pic_offset_y_in_luma_samples[i] shall be an integer multiple ofCTB size.

According to exemplary embodiments, the Table 3sps_sub_pic_width_in_luma_samples[i] specifies the width of the i-thsubpicture in units of luma samples.sps_sub_pic_width_in_luma_samples[i] shall be an integer multiple of CTBsize.

According to exemplary embodiments, the Table 3sps_sub_pic_height_in_luma_samples[i] specifies the height of the i-thsubpictue in units of luma samples.sps_sub_pic_height_in_luma_samples[i] shall be an integer multiple ofCTB size.

According to exemplary embodiments, the Table 3sps_num_output_sub_pic_sets_minus1 plus 1 specifies the number of outputsubpicture set in the coded vide sequence referring to the SPS. When notpresent, the value of sps_num_output_layer_sets_minus1 is inferred to beequal to 0.

According to exemplary embodiments, the Table 3sps_num_output_sub_pic_minus1[i] specifies the number of subpictures ofthe i-th output subpicture set.

According to exemplary embodiments, the Table 3 sps_sub_pic_id_oss[i][j] specifies the subpicture ID of the j-th output subpicture of thei-th subpicture. The length of sps_sub_pic_id_oss [i][j] syntax elementis sps_subpic_id_length_minus1+1 bits. When not present,sps_sub_pic_id_oss [i][j] is inferred to be equal to j, for each i inthe range of 0 to sps_num_output_subpic_minus1[i], inclusive.

For PPS, a Table 4 may be considered:

TABLE 4 Descriptor _pic_parameter_set_rbsp( ) { ... pic _(—) width _(—)in _(—) luma _(—) samples ue(v) pic _(—) height _(—) in _(—) luma _(—)samples ue(v) subpics _(—) updated _(—) flag u(1)if(subpics_updated_flag) { pps _(—) sub _(—) pic _(—) id _(—) present_(—) flag u(1) if( pps_sub_pic_id_present_flag ) pps _(—) sub _(—) pic_(—) id _(—) length _(—) minus1 ue(v) pps _(—) num _(—) sub _(—) pic_(—) in _(—) pic _(—) minus1 ue(v) for( i = 0; i <=sps_num_sub_pic_in_pic_minus1; i++) { if( pps_sub_pic_id_present_flag )pps _(—) sub _(—) pic _(—) id[ i ] u(v) if( j > 0 ) { pps _(—) sub _(—)pic _(—) offset _(—) x _(—) in _(—) luma _(—) samples[ i ][ j ] ue(v)pps _(—) sub _(—) pic _(—) offset _(—) y _(—) in _(—) luma _(—) samples[i ][ j ] ue(v) } pps _(—) sub _(—) pic _(—) width _(—) in _(—) luma _(—)samples[ i ][ j ] ue(v) pps _(—) sub _(—) pic _(—) height _(—) in _(—)luma _(—) samples[ i ][ j ] ue(v) } } ... }

According to exemplary embodiments, the Table 4 subpics_updated_flagequal to 1 specifies that the layout information of subpictures isupdated by the syntax elements indicating the updated subpicture layoutinformation in PPS. subpics_updated_flag equal to 0 specifies that thelayout information of subpictures is not updated.

According to exemplary embodiments, the Table 4pps_sub_pic_id_present_flag equal to 1 specifies that pps_sub_pic_id [i]is present in PPS. sps_sub_pic_idpresent_flag equal to 0 specifies thatpps_sub_pic_id[i] is not present in PPS.

According to exemplary embodiments, the Table 4pps_sub_pic_id_length_minus1 plus 1 specifies the number of bits used torepresent the syntax element pps_sub_pic_id[i][j]. The value ofpps_sub_pic_id_length_minus1 shall be in the range of 0 to 15,inclusive. When not present, the value of pps_sub_pic_id length_minus1is inferred to be equal to Ceil(Log 2(Max(2,pps_num_sub_pic_in_pic_minus1+1)))−1.

According to exemplary embodiments, the Table 4 pps_sub_pic_id[i]specifies the subpicture ID of the i-th subpicture. The length of thepps_sub_pic_id[i] syntax element is sps_sub_pic_id_length_minus1+1 bits.When not present, pps_sub_pic_id[i] is inferred to be equal to i, foreach i in the range of 0 to pps_num_sub_pic_in_pic_minus1, inclusive.

According to exemplary embodiments, the Table 4pps_sub_pic_offset_x_in_luma_samples[i] specifies the horizontal offset,in units of luma samples, of the top-left corner luma sample of the i-thsubpicture relative to the top-left corner luma sample of the composedpicture. When not present, the value ofpps_sub_pic_offset_x_in_luma_samples[i] is inferred to be equal to 0.pps_sub_pic_offset_x_in_luma_samples[i] shall be an integer multiple ofCTB size.

According to exemplary embodiments, the Table 4pps_sub_pic_offset_y_in_luma_samples[i] specifies the vertical offset,in units of luma samples, of the top-left corner luma sample of the i-thsubpictue relative to the top-left corner luma sample of the composedpicture. When not present, the value ofsps_sub_pic_offset_y_in_luma_samples[i] is inferred to be equal to 0.sps_sub_pic_offset_y_in_luma_samples[i] shall be an integer multiple ofCTB size.

According to exemplary embodiments, the Table 4pps_sub_pic_width_in_luma_samples[i] specifies the width of the i-thsubpicture in units of luma samples.pps_sub_pic_width_in_luma_samples[i] shall be an integer multiple of CTBsize.

According to exemplary embodiments, the Table 4pps_sub_pic_height_in_luma_samples[i] specifies the height of the i-thsubpictue in units of luma samples.pps_sub_pic_height_in_luma_samples[i] shall be an integer multiple ofCTB size.

According to exemplary embodiments, the Table 4pps_num_output_sub_pic_sets_minus1 plus 1 specifies the number of outputsubpicture set in the pictures referring to the PPS. When not present,the value of pps_num_output_layer_sets_minus1 is inferred to be equal to0.

According to exemplary embodiments, the Table 4pps_num_output_sub_pic_minus1[i] specifies the number of subpictures ofthe i-th output subpicture set.

According to exemplary embodiments, the Table 4 pps_sub_pic_id_oss[i][j] specifies the subpicture ID of the j-th output subpicture of thei-th subpicture. The length of pps_sub_pic_id_oss [i][j] syntax elementis pps_sub_pic_id length_minus1+1 bits. When not present,pps_sub_pic_id_oss [i][j] is inferred to be equal to j, for each i inthe range of 0 to pps_num_output_subpic_minus1[i], inclusive.

The techniques for signaling adaptive resolution parameters describedabove, can be implemented as computer software using computer-readableinstructions and physically stored in one or more computer-readablemedia. For example, FIG. 7 shows a computer system (700) suitable forimplementing certain embodiments of the disclosed subject matter.

The computer software can be coded using any suitable machine code orcomputer language, that may be subject to assembly, compilation,linking, or like mechanisms to create code comprising instructions thatcan be executed directly, or through interpretation, micro-codeexecution, and the like, by computer central processing units (CPUs),Graphics Processing Units (GPUs), and the like.

The instructions can be executed on various types of computers orcomponents thereof, including, for example, personal computers, tabletcomputers, servers, smartphones, gaming devices, internet of thingsdevices, and the like.

The components shown in FIG. 7 for computer system (700) are exemplaryin nature and are not intended to suggest any limitation as to the scopeof use or functionality of the computer software implementingembodiments of the present disclosure. Neither should the configurationof components be interpreted as having any dependency or requirementrelating to any one or combination of components illustrated in theexemplary embodiment of a computer system (700).

Computer system (700) may include certain human interface input devices.Such a human interface input device may be responsive to input by one ormore human users through, for example, tactile input (such as:keystrokes, swipes, data glove movements), audio input (such as: voice,clapping), visual input (such as: gestures), olfactory input (notdepicted). The human interface devices can also be used to capturecertain media not necessarily directly related to conscious input by ahuman, such as audio (such as: speech, music, ambient sound), images(such as: scanned images, photographic images obtain from a still imagecamera), video (such as two-dimensional video, three-dimensional videoincluding stereoscopic video).

Input human interface devices may include one or more of (only one ofeach depicted): keyboard (701), mouse (702), trackpad (703), touchscreen (710), joystick (705), microphone (706), scanner (707), camera(708).

Computer system (700) may also include certain human interface outputdevices. Such human interface output devices may be stimulating thesenses of one or more human users through, for example, tactile output,sound, light, and smell/taste. Such human interface output devices mayinclude tactile output devices (for example tactile feedback by thetouch-screen (710), or joystick (705), but there can also be tactilefeedback devices that do not serve as input devices), audio outputdevices (such as: speakers (709), headphones (not depicted)), visualoutput devices (such as screens (710) to include CRT screens, LCDscreens, plasma screens, OLED screens, each with or without touch-screeninput capability, each with or without tactile feedback capability—someof which may be capable to output two dimensional visual output or morethan three dimensional output through means such as stereographicoutput; virtual-reality glasses (not depicted), holographic displays andsmoke tanks (not depicted)), and printers (not depicted).

Computer system (700) can also include human accessible storage devicesand their associated media such as optical media including CD/DVD ROM/RW(720) with CD/DVD or the like media (721), thumb-drive (7220, removablehard drive or solid state drive (723), legacy magnetic media such astape and floppy disc (not depicted), specialized ROM/ASIC/PLD baseddevices such as security dongles (not depicted), and the like.

Those skilled in the art should also understand that term “computerreadable media” as used in connection with the presently disclosedsubject matter does not encompass transmission media, carrier waves, orother transitory signals.

Computer system (700) can also include interface to one or morecommunication networks. Networks can for example be wireless, wireline,optical. Networks can further be local, wide-area, metropolitan,vehicular and industrial, real-time, delay-tolerant, and so on. Examplesof networks include local area networks such as Ethernet, wireless LANs,cellular networks to include GSM, 3G, 4G, 5G, LTE and the like, TVwireline or wireless wide area digital networks to include cable TV,satellite TV, and terrestrial broadcast TV, vehicular and industrial toinclude CANBus, and so forth. Certain networks commonly require externalnetwork interface adapters that attached to certain general purpose dataports or peripheral buses (749) (such as, for example USB ports of thecomputer system (700); others are commonly integrated into the core ofthe computer system (700) by attachment to a system bus as describedbelow (for example Ethernet interface into a PC computer system orcellular network interface into a smartphone computer system). Using anyof these networks, computer system (700) can communicate with otherentities. Such communication can be uni-directional, receive only (forexample, broadcast TV), uni-directional send-only (for example CANbus tocertain CANbus devices), or bi-directional, for example to othercomputer systems using local or wide area digital networks. Certainprotocols and protocol stacks can be used on each of those networks andnetwork interfaces as described above.

Aforementioned human interface devices, human-accessible storagedevices, and network interfaces can be attached to a core (740) of thecomputer system (700).

The core (740) can include one or more Central Processing Units (CPU)(741), Graphics Processing Units (GPU) (742), specialized programmableprocessing units in the form of Field Programmable Gate Areas (FPGA)(743), hardware accelerators for certain tasks (744), and so forth.These devices, along with Read-only memory (ROM) (745), Random-accessmemory (746), internal mass storage such as internal non-user accessiblehard drives, SSDs, and the like (747), may be connected through a systembus (748). In some computer systems, the system bus (748) can beaccessible in the form of one or more physical plugs to enableextensions by additional CPUs, GPU, and the like. The peripheral devicescan be attached either directly to the core's system bus (748), orthrough a peripheral bus (749). Architectures for a peripheral businclude PCI, USB, and the like.

CPUs (741), GPUs (742), FPGAs (743), and accelerators (744) can executecertain instructions that, in combination, can make up theaforementioned computer code. That computer code can be stored in ROM(745) or RAM (746). Transitional data can be also be stored in RAM(746), whereas permanent data can be stored for example, in the internalmass storage (747). Fast storage and retrieve to any of the memorydevices can be enabled through the use of cache memory, that can beclosely associated with one or more CPU (741), GPU (742), mass storage(747), ROM (745), RAM (746), and the like.

The computer readable media can have computer code thereon forperforming various computer-implemented operations. The media andcomputer code can be those specially designed and constructed for thepurposes of the present disclosure, or they can be of the kind wellknown and available to those having skill in the computer software arts.

As an example and not by way of limitation, the computer system havingarchitecture (700), and specifically the core (740) can providefunctionality as a result of processor(s) (including CPUs, GPUs, FPGA,accelerators, and the like) executing software embodied in one or moretangible, computer-readable media. Such computer-readable media can bemedia associated with user-accessible mass storage as introduced above,as well as certain storage of the core (740) that are of non-transitorynature, such as core-internal mass storage (747) or ROM (745). Thesoftware implementing various embodiments of the present disclosure canbe stored in such devices and executed by core (740). Acomputer-readable medium can include one or more memory devices orchips, according to particular needs. The software can cause the core(740) and specifically the processors therein (including CPU, GPU, FPGA,and the like) to execute particular processes or particular parts ofparticular processes described herein, including defining datastructures stored in RAM (746) and modifying such data structuresaccording to the processes defined by the software. In addition or as analternative, the computer system can provide functionality as a resultof logic hardwired or otherwise embodied in a circuit (for example:accelerator (744)), which can operate in place of or together withsoftware to execute particular processes or particular parts ofparticular processes described herein. Reference to software canencompass logic, and vice versa, where appropriate. Reference to acomputer-readable media can encompass a circuit (such as an integratedcircuit (IC)) storing software for execution, a circuit embodying logicfor execution, or both, where appropriate. The present disclosureencompasses any suitable combination of hardware and software.

While this disclosure has described several exemplary embodiments, thereare alterations, permutations, and various substitute equivalents, whichfall within the scope of the disclosure. It will thus be appreciatedthat those skilled in the art will be able to devise numerous systemsand methods which, although not explicitly shown or described herein,embody the principles of the disclosure and are thus within the spiritand scope thereof

What is claimed is:
 1. A method for video coding performed by at leastone processor, the method comprising: obtaining video data; parsing avideo parameter set (VPS) syntax of the video data; determining whethera value of a syntax element of the VPS syntax indicates a picture ordercount (POC) value of an access unit (AU) of the video data; and settingat least one of a plurality of pictures, slices, and tiles of the videodata to the AU based on the value of the syntax element.
 2. The methodfor video coding according to claim 1, wherein the value of the syntaxelement indicates a number consecutive ones of the plurality ofpictures, slices, and tiles of the video data to be set to the AU. 3.The method for video coding according to claim 1, wherein VPS syntax iscontained in a VPS of the video data and identifying a number of atleast one type of enhancement layers of the video data.
 4. The methodfor video coding according to claim 1, further comprising: determiningwhether the VPS syntax comprises a flag indicating whether the POC valueincreases uniformly per AU.
 5. The method for video coding according toclaim 4, further comprising: calculating, in response to determiningthat the VPS comprises the flag and that the flag indicates that the POCvalue does not increase uniformly per AU, an access unit count (AUC)from the POC value and a picture level value of the video data.
 6. Themethod for video coding according to claim 4, further comprising:calculating, in response to determining that the VPS comprises the flagand that the flag indicates that the POC value does increase uniformlyper AU, an access unit count (AUC) from the POC value and a sequencelevel value of the video data.
 7. The method for video coding accordingto claim 1, further comprising: determining whether the VPS syntaxcomprises a flag indicating whether at least one of the pictures isdivided into a plurality of sub-regions.
 8. The method for video codingaccording to claim 7, further comprising: setting, in response todetermining that the VPS syntax comprises the flag and that the flagindicates that the at least one of the pictures is not divided into theplurality of sub-regions, an input picture size of the at least one ofthe pictures to a coded picture size signaled in a sequence parameterset (SPS) of the video data.
 9. The method for video coding according toclaim 7, further comprising: determining, in response to determiningthat the VPS syntax comprises the flag and that the flag indicates thatthe at least one of the pictures is divided into the plurality ofsub-regions, whether the SPS comprises syntax elements signaling offsetscorresponding to a layer of the video data.
 10. The method for videocoding according to claim 9, wherein the offsets comprise an offset inan width direction and an offset in a height direction.
 11. An apparatusfor video coding, the apparatus comprising: at least one memoryconfigured to store computer program code; at least one processorconfigured to access the computer program code and operate as instructedby the computer program code, the computer program code including:obtaining code configured to cause the at least one processor to obtainvideo data; parsing code configured to cause the at least one processorto parse a video parameter set (VPS) syntax of the video data;determining code configured to cause the at least one processor todetermine whether a value of a syntax element of the VPS syntaxindicates a picture order count (POC) value of an access unit (AU) ofthe video data; and setting code configured to cause the at least oneprocessor to set at least one of a plurality of pictures, slices, andtiles of the video data to the AU based on the value of the syntaxelement.
 12. The apparatus for video coding according to claim 11,wherein the value of the syntax element indicates a number consecutiveones of the plurality of pictures, slices, and tiles of the video datato be set to the AU.
 13. The apparatus for video coding according toclaim 11, wherein VPS syntax is contained in a VPS of the video data andidentifying a number of at least one type of enhancement layers of thevideo data.
 14. The apparatus for video coding according to claim 11,wherein the determining code is further configured to cause the at leastone processor to determine whether the VPS syntax comprises a flagindicating whether the POC value increases uniformly per AU.
 15. Theapparatus for video coding according to claim 14, further comprising:calculating code configured to cause the at least one processor tocalculate, in response to determining that the VPS comprises the flagand that the flag indicates that the POC value does not increaseuniformly per AU, an access unit count (AUC) from the POC value and apicture level value of the video data.
 16. The apparatus for videocoding according to claim 14, further comprising: calculating codeconfigured to cause the at least one processor to calculate, in responseto determining that the VPS comprises the flag and that the flagindicates that the POC value does increase uniformly per AU, an accessunit count (AUC) from the POC value and a sequence level value of thevideo data.
 17. The apparatus for video coding according to claim 11,wherein the determining code is further configured to cause the at leastone processor to determine whether the VPS syntax comprises a flagindicating whether at least one of the pictures is divided into aplurality of sub-regions.
 18. The apparatus for video coding accordingto claim 17, wherein the setting code is further configured to cause theat least one processor to set, in response to determining that the VPSsyntax comprises the flag and that the flag indicates that the at leastone of the pictures is not divided into the plurality of sub-regions, aninput picture size of the at least one of the pictures to a codedpicture size signaled in a sequence parameter set (SPS) of the videodata.
 19. The apparatus for video coding according to claim 17, whereinthe determining code is further configured to cause the at least oneprocessor to determine, in response to determining that the VPS syntaxcomprises the flag and that the flag indicates that the at least one ofthe pictures is divided into the plurality of sub-regions, whether theSPS comprises syntax elements signaling offsets corresponding to a layerof the video data.
 20. A non-transitory computer readable medium storinga program causing a computer to execute a process, the processcomprising: obtaining video data; parsing a video parameter set (VPS)syntax of the video data; determining whether a value of a syntaxelement of the VPS syntax indicates a picture order count (POC) value ofan access unit (AU) of the video data; and setting at least one of aplurality of pictures, slices, and tiles of the video data to the AUbased on the value of the syntax element.